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Can anyone recommend a good PCB layout program that's not prohibitively expensive and has a reasonably "standard" UI? I used to use ExpressPCB, but you can only use that with the one manufacturer. I see a lot of people using Eagle, but I really dislike the modal, AutoCAD-style user interface, I'd prefer something that works more like a conventional drawing program. More power to you if Eagle works for you, but my brain just doesn't want to work that way for some reason. Schematic capture and PCB validation to a schematic are great features; autorouting and simulation aren't necessary. I'd also like to do slightly larger boards than the free version of Eagle allows, probably I don't really need more than 2 sides/layers.
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Apr 5, 2012 05:18
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Krenzo posted:DipTrace Thanks. I just spent a little time trying this out. There are some other oddities to get used to, but so far it looks like it will work out reasonably well. 300 pads might be a bit limiting for me, but I don't necessarily need free, just not $1000's. Last time I looked KiCad was Linux only; I have a Linux machine but I don't really use it for a desktop, so I'll give DipTrace first crack at it. I haven't had a chance to try DesignSpark yet...
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Apr 6, 2012 03:58
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Rahul posted:Shouldn’t the discharge pin be connected below R3? I'm guessing you'll want the boost converter to be adjustable: it's not regulated, so the voltage you put across the EL may vary depending on input voltage, how the 2nd timer is adjusted, etc. But I'm not a boost converter expert. (In case you're really just interested in a working display and not necessarily the intricacies of inverters, Sparkfun does sell a 12V EL inverter...)
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Apr 8, 2012 23:01
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Hidden Under a Hat posted:It also means it won't actually change it's resistance characteristics right? But different resistor types have different temperature dependance, and depending on what that resistor does in the circuit, you might or might not need it to be stable. Some resistors are made to be very stable for precision circuits (<50ppm/C), and others are made to be deliberately unstable for sensing or compensating for temperature variations (> 3000ppm/C). Often you can cancel out temperature variations as long as you don't have hotspots (from any part handling a lot of power) nearby; a voltage divider will tend to be reasonably stable as long as both resistors are at the same temperature. I don't do a lot of high power stuff, though, so I don't know if high-power resistors tend to have high temperature coefficients or low ones. In the circuit you're talking about, though, the exact resistance won't be critical. If what you're trying to do is dim an LED string, you'd be better off switching the string on and off with a series transistor, using pulse width modulation. It's a more complicated circuit, but it will perform better, and you can vary the brightness more or less continuously.
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Apr 13, 2012 02:11
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TVarmy posted:even though the chips are a dollar, I don't like waiting for new ones in the mail. I'm slightly embarrassed by the number of parts I have squirreled away "just in case".
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May 6, 2012 03:41
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Chainclaw posted:There's going to be a mini Maker Faire in Seattle this year June 2nd and 3rd Oh hey, that's handy to know...
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May 8, 2012 06:09
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On the position sensing thing. It's not passive and it requires line of sight for a minimum number of sensors (redundancy helps), but: A professor of mine some years worked on precisely locating objects using DSP and variable frequency sonar chirps. The idea was you send out this frequency modulated chirp and use a DSP to correlate the transmitted signals with the received chirp. Convolving the chirp signal with an echo would give you correlation at sample rate intervals, and you could work out how long it took the signal to reach the receiver fairly precisely (better than wavelength resolution). It relied on having a fair amount of bandwidth and DSP horsepower (the latter should be cheap today though, this was more than 10 years ago), and you needed to synchronize the transmitted chirp timing with when you start sampling at the receiver, and of course to get a 2D or 3D location, you'd need to measure more than one receiver. I wonder if you could implement something like this with ultrasonic transducers? Do those transducers have a decent bandwidth or do they have a specific frequency they operate at? I don't recall what kind of resolution you could expect in air.
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May 9, 2012 06:07
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longview posted:It's also annoying me, since I see the flickering when I move my eyes. How hard is it to just switch at like 20 kHz where literally nobody could see it?
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Jun 7, 2012 21:38
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Delta-Wye posted:If you don't mind soldering/desoldering, you should just try it. Looking at the schematic, it shouldn't hurt anything; I don't think it will sound right but it could be an interesting experiment. I don't think the value 220K is especially critical there, but 220M is really huge, and the transistor probably won't be biased into conducting. If you have anything in the 100K-1M range that might work fine, depending on the transistor.
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Jun 30, 2012 03:00
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sixide posted:That looks to be true, though it won't be able to drive any sort of real load. Looks like you'll run into the upper rail and have a ton of distortion. It would help to short that LED, although it's not a Sparkfun project without an LED.
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Jun 30, 2012 03:21
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edmund745 posted:Because if I used direct hardware data transfer, I wouldn't want to use a printer port--and as I recall,,,,, any multiples of identical items on the USB port are enumerated in whatever order they are discovered by the OS. There would be no way to keep them straight from one use to the next. It's been a while since I did USB work but if I recall correctly, a device manufacturer can put a unique device id into a device's EEPROM so that when the device is enumerated the PC gets the id and knows which device is which. However, many manufacturers do not do this, because it requires programming a unique code into each device after its manufactured, which is a pain in the rear end, and that's why you often end up with enumeration problems when you add/remove devices. You might be able to find a single device that you can put on a USB that fans out to enough outputs for you. An FTDI USB-serial or USB-parallel can send commands to your microcontroller, and it can control as many outputs as you can manage to hook up and code for (with a protocol that's something like "send 45 pulses through output 11" or something). I'm not a stepper expert though, I'm not sure if you have particular timing concerns that you might need to account for in your protocol and whether that would be fast enough.
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Jul 4, 2012 03:32
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SupahDren posted:1) Can I use a different resistance pot in the circuit, say a 10kOhm one, or will that release the magic blue smoke somewhere? Chances are you'll be ok. A volume control is generally a voltage divider, and its the ratio that matters, not the exact resistance. You are reducing the input impedance of the amplifier a bit. If the amp is being driven by something with a highish output impedance, the pot will load it some and affect the overall amplitude. Chances are this is not a big deal, especially if you have a pre-amp before the volume control. That effect might be more if you have other passive components between your pre-amp and amp, however, such as tone controls. By the same token, the input impedance of the actual amp after your volume control loads the volume control, but since you're reducing the resistance that shouldn't be a problem. If you increased the resistance instead then you'd want to make sure the actual amp had higher input impedance. A 2X change is actually not that big in this context though.
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Jul 8, 2012 01:26
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Slanderer posted:Honestly, though, I'm still not sure on the point of grounding the case/frame of appliances with newer 3-prong plugs, since I've also read a ground current from a faulty appliance often won't trip a breaker, so you're hosed anyway! Grounding doesn't trip a breaker, it's to make sure there aren't potential differences between different grounds, or ground and a chassis or other metal part. Because neutral carries a lot of current (same current as hot), the voltage difference V=IR between neutral and ground can be more than you'd safely like, so you can't use neutral as a ground reference. (And it gets miswired from time to time.) Normally, there should be little current returned via ground as opposed to neutral. If a power supply is isolated vs. power and floating, it can get charged up well above "actual" ground (meaning whatever else a human might be in contact with); the metal is basically a capacitor. Properly grounded the charge gets returned to ground, but it shouldn't be a lot of current. In cases where there's a danger ground might end up carrying a lot of current, you turn off hot and neutral with a GCFI, which interrupts the power driving the current. A breaker that disconnects a ground would be dangerous.
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Jul 14, 2012 05:09
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For that circuit, you want audio taper. The ear has a log response to volume, so if you want a linear increase in perceived volume you need an exponential increase in input amplitude. It sounds like the pot might have a short in it. Did you try a different pot? A loudness tap was used back in the 70s/80s to implement volume dependent frequency compensation because the ear doesn't respond to high frequencies at low volume the same as at high volume. It basically added cost for a feature nobody understood or cared about and died out. I'm surprised anybody makes pots like that any more, unless Radio Shack is still selling inventory from the 80s.
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Jul 22, 2012 17:18
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Make sure that the pot, R2 and R3 are connected to the right ground, that is the voltage divider reference and not the negative battery terminal. The shields of your connectors should also be connected to this ground. Also, check that you have the + and - inputs of the amp connected correctly and the electrolytic caps the right way around. Dunno if that could cause your problem, but these are always good things to check when troubleshooting audio gear being difficult.
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Jul 23, 2012 00:25
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The mbed is a Cortex M3 and it does have wired ethernet and USB, though not built in Wifi. It's pretty a pretty low-effort system since you don't have to install tools yourself (though you can use it with regular ARM compilers) and programming it is a matter of dropping a bin file on it as if it were a USB flash drive, and it's got a fair number of C++ libraries available. eta: A wireless access point could be connected by Ethernet so you can use the existing TCP/IP libraries. If you connect a wifi dongle by USB that should work but I don't know what if any libraries are available for that. It also occurs to me that depending on how much IO you need, you might be able to find a hackable wireless router and mod it with something like OpenWRT. Base Emitter fucked around with this message at 08:05 on Aug 2, 2012 |
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Aug 2, 2012 08:00
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I'd suggest searching Kenmore-devoted repair sites to see if this is a common failure, and maybe try to find a schematic. I'm guessing it's not 19M, that's unusually large and would require a fairly high voltage to fail like that, and sub 1 ohm is fairly unusual although it could have been used for current sensing in series with a load, and if the load shorted it would easily burn. Chances are the heat burned the stripes and obscured the colors and that's why that 3rd stripe is white; I'm guessing its a 47-something 5% - but the something could be x10 ohm or x100K ohms  Chances are something else is the root cause and that needs to be fixed too. I repaired my Maytag washer a couple of times, which had an infamous problem with burning up the motor used to latch the door. The motor would fail short, kill the TRIAC on the controller board which also failed short, and then the gate resistor would burn like what you see on your board. All three parts needed to be identified and replaced. Fortunately for me, there were enough cases that repairmen were posting blogs and even selling parts kits for the issue. Good luck. They don't make appliances like they used to.
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Aug 12, 2012 16:44
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What about using a double pole DPDT switch? Then you've got 2 completely separate switch circuits to work with.
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Aug 13, 2012 20:51
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Ah, I misunderstood your post, I thought you needed to keep two separate circuits. I'm not that familiar with Xbox innards...
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Aug 14, 2012 02:59
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CapnBry posted:I have what I think is a basic op amp question. I tried building this circuit from the a TI application note (using a TL074CN): If you're using a single-ended power supply (The V- on the TL074 connected to ground), that chip can't pull its output all the way to ground. You need a bipolar supply, like +5V and -5V). Generally op amps don't like to be near supply limits unless you get one specifically designed for it (and then you trade off other stuff), and for a TL074 5V overall isn't much supply voltage, so you won't have a lot of output range. An alternative to a split supply is a different reference, on R3, to a voltage between ground. The simplest option is to replace R3 with a voltage divider between your upper and lower supply. For example, if you set R3a = R3b = 2R4, where R3a and R3b are the upper and lower half of the divider, the divider will look like one resistance equal to R4 to 2.5V. Your output will be centered at this voltage. But you'd still want an op amp that's design for smaller supply voltages than a TL074. Are you using matched resistors? A differential amp is only as good as the matching of its inputs. Especially important if you've got high gain; yours is 100, so if you have a 10mV difference between + and - because of resistor mismatching, that'll be 1V at the output, and it would be easy to get a 10mV error with a large common mode input and resistors that are only matched to 1% tolerance. A better solution is to make all four resistors equal and use a matched resistor array for all four. Then if you want gain, add a gain stage after it. (If you do single supply with a reference divider, you need 7 equal resistors, using two in series for each part of the voltage divider.) An opamp with better DC performance and less offset would be better for this particular application, like an LT1013 (which still wants bipolar supplies). There are more modern opamps that work a lot better at lower supply voltages, including ones designed for sensors, but since I mostly do old school analog audio stuff I'm not that familiar with them.
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Nov 1, 2012 04:11
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CapnBry posted:I don't have matched resistors, just some 1% tolerance jobbers that I've got left over from another project. I figured I'd be able to account for any differences either in software or by placing other resistors in parallel to balance then out. I'm not sending a man to the moon, I'm just playing around with weighing things on my workbench. I'll keep your design notes in mind for when I decide to make a quality system. I'm trying to make do at this point with just parts I've got already without making a mouser order. You can use your unmatched 1% resistors and get 1% (or so) of error if you design your amplifier to have a gain of 1 (all the resistors equal). You mostly have an issue matching your resistors if you want high gain in the differential stage, because the error between the two input resists will be amplified by the gain. You can still have a gain of 100, just make the differential amp gain 1 and add a single ended, gain 100 amp after it. Sorry if I was unclear. You should be able to make this work with the bits you've got...
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Nov 2, 2012 02:27
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Eyeballing it and not doing any circuit analysis, I'd say you've got distortion, basically soft clipping, at the upper half of your output voltage range. It looks wide because the distortion isn't symmetric for the upper and lower half of the waveform. Try reducing the gain to see if you get less distortion. You might even try increasing the supply voltage from 8 to say 12V just to see if the output eyeballs better, just because it will give you more headroom. If you have a sinusoidal input, then rolloff from capacitors (which are linear) should only affect the gain; the waveform would only be distorted for nonsinusoidal inputs. Transistors do have frequency limits, but 200uS period is only 5KHz, nowhere near the limit (which is somewhere in MHz). (Also it looks like your input is 40 mV peak to peak, or 14 mV RMS, in case you were really expecting it to be lower.)
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Nov 4, 2012 04:09
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peepsalot posted:How can the voltage potential reverse on the inductor, and yet the current flows the same direction? It's physics. The magnetic field created by a current flowing through a conductor stores energy. When the current is turned off, that energy has to go somewhere; it induces a current back onto the same conductor. In effect, inductors "don't like" their current changing. A current through an inductor will keep going for as long as it can get energy back out of the magnetic field. This is why a series inductor filters out high frequency AC. The reversal in voltage is related. If current is being pushed along the inductor by the changing magnetic field, the moving charge has to come from somewhere, and there's no complete path for it to follow. The movement of charge creates a large potential difference between the two ends of the inductor. Adding the protection diode provides a path for the current to return after the circuit is turned off without interfering with normal operation.
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Nov 6, 2012 08:24
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I'm strictly a hobbyist and don't have any formal EE education, but I was physics student (i.e. dealt with a lot of math and electromagnetism), and I've spent some years doing analog synthesizer stuff, where it helps to really understand bipolar transistors. Voltage control in analog music relies on bipolar transistor behavior. Understanding transistors was definitely a struggle, though, and I do think a lot of hobbyists take a "cookbook" approach of dealing with well-known circuits. Most of the people who would actually sit down and design a VCO are EEs off the clock.
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Nov 16, 2012 03:24
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movax posted:Seriously no one in this thread should feel dumb / useless for wanting to do electronics stuff without math knowledge I think the main advantage of being a math nerd is confidence when you encounter some, not actual mad math skills.
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Nov 16, 2012 05:43
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Martytoof posted:I want to murder whoever came up with the resistor colour scheme. I'm partially color-blind, the stripes all say "hey, I'm a resistor!" and I measure everything. Of course, these days I also need a giant magnifying lens to read the numbers on capacitors, so...
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Nov 18, 2012 01:16
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movax posted:Ran across an interesting question today, how exactly did 5V/3.3V/etc get "standardized"? De facto standards from the processes/companies of the time? Can't say about 3.3V. However, 5V comes from the design of the original bipolar TTL output stage. You'd want a push-pull pair (like a class B amplifier) but when you are trying to make ICs as cheaply as possible, you're much happier if you can build everything with just NPN transistors. Putting PNP transistors on a chip with NPNs requires extra processing steps, and PNP transistors require more real-estate and give poorer performance. So TTL has this "totem-pole" output which basically has a phase splitter and a high-side and low-side driver stacked on top of one another through two of diodes (the totem pole) that can be made with all NPN transistors. When that first transistor conducts, the bases of both driver transistors are at the nearly same potential. The lower transistor is biased into conducting, but the upper transistor stays off because the drop across the diodes makes its emitter more positive. When the first transistor is off, the base of the lower transistor goes to ground, while the upper transistor turns on. There's a fairly narrow range of supply voltages where the biasing for this works, 4.5-5.5V. Go outside those ranges and either both transistors are on at the same time (all that toasty current from Vcc to ground) or neither will turn on. So, the 5V standard comes from that. MOSFETs, from which we get CMOS, are much more tolerant of supply variation, because they appear in complementary pairs and don't rely on biasing. Early CMOS ICs ran from 3V to 18V, and you see 4000 series parts in audio systems with +/-5V or even 0-15V supplies. The good old 1802 microprocessor could run off an unregulated 9V battery. A lot of early MOS chips were made in non-complementary NMOS (and occasionally PMOS) because they required fewer processing steps, however, and were cheaper to manufacture. The biasing plus the base currents of bipolar transistors, vs high-impedance gate complementary pairs, is why CMOS is so much more power efficient. Eventually those advantages overcame any objections to extra processing steps.
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Nov 22, 2012 07:07
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longview posted:Wow, I didn't know that, so is that why chips tend to toast themselves if you apply too much voltage? That's one way, for classic TTL. Other circuit types have different failure modes for other reasons. Bipolar ICs tend to have a lot of reverse biased junctions in them (device to substrate), and those junctions can act like Zener diodes and start conducting at higher than intended voltage. Some analog circuits will have operating currents set by a few internal resistors and a bunch of current mirrors, so increasing the supply voltage will increase currents all over the circuit. Ingenious ways to blow chips up probably competes with ways to design them...
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Nov 22, 2012 10:06
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longview posted:I could use a 555 but I tested the circuit with a square wave and I didn't like it, plus the capacitive coupling really messes up the pulse shape. Buffering the voltage on the cap will give you an sort-of-triangle wave, especially if it's near 50% duty cycle. However, it's probably simpler to build a triangle oscillator with a dual opamp, like this: http://www-k.ext.ti.com/SRVS/Data/ti/KnowledgeBases/analog/document/faqs/sscco8.htm There's ways to shape a triangle to an approximate sine if you really want a sine wave, generally by soft-clipping the signal. A triangle isn't a terrible approximation to a sine depending on what you're using it for, though.
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Dec 2, 2012 01:35
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Martytoof posted:Is there an IC with X number of resistors that I can use for a 7 segment display or do I just need to put in 7 discrete resistors? Yes, you can get resistor arrays in a variety of configurations, including 7 in a 14-pin DIP. There's also display driver chips with current source drivers where you can set segment current with a single resistor. For example, at Digikey: http://www.digikey.com/scripts/dkse...16=6510&stock=1 Base Emitter fucked around with this message at 02:52 on Dec 9, 2012 |
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Dec 9, 2012 02:50
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^^^ edit, he says it's all analog? Hmm... wonder how he responded to the touch sensing then.ANIME AKBAR posted:Well it's almost certainly a preprogrammed, timed sequence which he's just synchronizing his finger to. He's not actually controlling anything directly. A 9V battery case has plenty of room for whatever sort of driver circuitry. But I can't think of how each LED is controlled by the electronics, unless he's actually able to fabricate LEDs with simple integrated circuitry. LEDs with built in flashing controllers exist, but those can't replicate this behavior. He's got an earlier video involving switches, and that's been been explained, I assume this is just a fancier, craftier version. The older one had an AC circuit in the battery, with a smaller battery inside. Two of the LEDs had opposite polarity to each other, with a hidden diode across each one in opposite polarity, so the AC would illuminate both. If you opened a switch in series that had another diode in parallel to it, the opposite LED would go out. Put two switches in series, and you can turn off either LED. The third LED involved a capacitor filtering the AC somehow but I can't remember the details... it might have involved blocking a DC component or something. I imagine for this third one, there's a microcontroller with two three-state output pins, and he can do capacitive sensing on the wire as well, and has the same bits in parallel with the LEDs. It seems like if you were fairly careful you could solder surface mount LEDs, diodes and/or caps together and them put them in plastic that looks like a through-hole LED. In the old circuit he was just crafty about hiding the extra parts under the LEDs.
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Dec 14, 2012 06:51
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Delta-Wye posted:http://www.amazon.com/Weller-WLC100-40-Watt-Soldering-Station/dp/B000AS28UC/ I have a Weller WPCPT and its been a reliable workhorse. I'm not sure why it's more expensive than these others now, it was cheaper when I bought it but that was about 12 years ago. Take it as a weller endorsement I guess...
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Dec 27, 2012 08:54
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Double-regulating and an LC filter is a bit overkill, though. The solution is to use a slightly-less cheap-rear end Taiwanese charger (or DC/DC converter if you're building your own). For iDevices, Apple puts resistor voltage dividers on the D+ and D- lines. There's information around the net, lots of people have reverse engineered it for just this purpose. It's pretty simple to do, I built a charger (and audio line out adapter) for mine. If you don't care about iPads you can just short D+ and D- together (although it occurs to me I'm not sure how other tablets sense charge current, or if they bother, and I'm not sure if the new connector changes anything).
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Dec 28, 2012 19:48
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Slanderer posted:Maybe some guys with big glasses and pocket protectors in the 50's did this kind of thing in labs, with big filters made using tube op amps and other crazy poo poo, but the golden age of analog has long since passed. We have forgotten their works, and will never again achieve their glory. I have to admit, an analog channel vocoder is on my list of cool-if-impractical-someday projects. Solid-state, though. I think you can do some basic DSP type stuff on ARM processors, I've implemented a basic string simulation on an mbed (which is another nice option if you are comfortable with C++). The IIR biquad filter is the digital equivalent of the basic two-pole filter stage in the analog domain. If you just want to build up some filters, and you'd prefer to implement it digitally, look that up and use it as a building block.
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Dec 31, 2012 03:35
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icantfindaname posted:I'm working on the project I mentioned earlier (here) and it says I should put resistors on each of the LEDs. I'm assuming they mean the common cathode/anode and not the 3 color pins? I'm new to this so please bear with me. Actually you want them on each of the three color pins. Each color is actually a separate LED, and there are three in each package. The resistors are used to limit the current through one LED. If you have one resistor for multiple LEDs, most of the current will tend to go through whichever LED has the lowest voltage drop (which is why its recommended to use a resistor for each). Different LEDs can vary due to manufacturing variation, but different colors will definitely have pretty big differences. As a result, a common resistor might result in only the red LED lighting up when you turn on, say, red and green. vvv just on the colors.
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Jan 14, 2013 07:37
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Parallel Paraplegic posted:So I'm trying to figure out what the heck I'm doing wrong here. I'm trying to recreate this circuit for a CMOS NAND gate, only using BJT's. So this circuit but with discrete PNP and NPN BJT transistors:http://forums.somethingawful.com/editpost.php?action=editpost&postid=412192111 Hard to say 100% without seeing the schematic as built, so, do you have PNP transistors above, emitters to Vdd, and NPN below, B's emitter to Vss, and the two bases B connected directly together? On a bipolar transistor, the base-emitter junction looks like a diode, so if so, you'd basically have two diodes between Vdd and Vss, even with all the transistors off. With MOSFETs, the gates are insulated and don't source or sink current whether the transistors are on or off (they require charge while switching on or off, like charging a capacitor) which is a pretty significant difference.
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Feb 4, 2013 03:14
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Parallel Paraplegic posted:Really this is more of a "CMOS gates are neato, I wonder if I can build a similar one with the stuff I have laying around" thing, not something I'll probably wind up using outside of playing around with it. The point is more to replicate the original diagram I posted in some form or another rather than needing this to actually do something in another project. Thanks for the help though Actually, it's not hard to build RTL, DTL, or TTL gates with discrete components (in the latter case, making most outputs open collector simplifies things and with bipolar logic you generally pull LEDs down from Vcc anyway). Somebody made a kit for a digital clock with discrete logic...
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Feb 5, 2013 07:07
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Delta-Wye posted:The problem with "how do I select parts for guitar pedals" is that small details in the transistors can color the sound significantly, complicating choosing one compared to most applications. Hell, a stack of the same make and model can produce different sounds across units. That latter point is important, though - unless you get a transistor for a particular purpose (high current, high beta, etc) manufacturing variations can swamp difference between models. While its not wrong to pick exact NOS transistors for a project, it's also not wrong, 95% of the time, to just use 2N3904/6 or BC550/560s for everything (assuming you get the pinout right, they're different), and its not wrong to just try random transistors of the right polarity/pinout until you find one you like. Of course, that's assuming you want "a good sound" rather than "THE right sound". The classic TB303, originals even more than clones, had a reputation for some models sounding great and others garbage; it might have been finicky and superstitious users but it might also have been huge manufacturing variations in transistors that all had the same part number stamped on the package. If a circuit calls for a germanium type, though, do try it with a germanium transistor. The big difference is Ge's have lower Vbe and lower beta than Si, and that can make a big difference. A lot of NOS germaniums however were originally used for switches (like the 2N404 originally used in CDC computers), which illustrates how relatively interchangeable small-signal transistors can be. There's also cases where high beta is important, like 2N5172, but that's unusual. I have an old Tek 454 scope that had a messed up brightness control that turned out to be a failed transistor, unmarked and in an old style package not used any more. After figuring out the pinout and polarity I just started sticking transistors in the socket, which immediately fixed the problem, then tried a few others until I found one that worked best (in terms of control range).
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Feb 13, 2013 02:59
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Otto Skorzeny posted:How much does beta vary from unit to unit these days? The art of electronics 2e mentions the problem and says that values can frequently vary from nominal by a factor of 2(!) - has the situation improved at all in the intervening 20-some years? I honestly don't know... I'm a hobbyist rather than an industry guy and most of the sources I rely on are that old at least. It wouldn't surprise me if it hasn't changed that much, most of the innovations in the last couple decades seem to have been in MOSFETs.
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Feb 13, 2013 03:19
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| # ¿ May 9, 2024 02:59 |
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What's relatively cheap and compact, and do you want to "record live" or play back a prerecorded track? The main thing is 4 minutes of audio requires a respectable amount of memory (for a single cheap chip). Sparkfun has an Arduino shield that's got MP3 playback and a memory card interface but its $40, and you need an Arduino, some programming, a memory card, and an MP3 file. https://www.sparkfun.com/products/10628 Of course once you have the basic platform you can hook up all kinds of extras, triggers, etc.
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Feb 19, 2013 03:37
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