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Low speed, dual-channel analog inputs can be had with the gameport. Slap a few cheap-as-hell sound cards in the system, and you have a gameport per, and the microphone and line-in jacks as well.
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Mar 28, 2011 05:45
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insta posted:Low speed, dual-channel analog inputs can be had with the gameport. Slap a few cheap-as-hell sound cards in the system, and you have a gameport per, and the microphone and line-in jacks as well. Joystick ports are really terrible and not very accurate. If you want something a bit better, an arduino or an MSP430 will give you something faster and more accurate but still cheap.
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Mar 28, 2011 07:11
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crabrock posted:What's the cheapest option for passing signals into a PC? When I google "analog inputs for PC" I just find really really expensive cards... Are there any cheaper options that are standard or anything? Well, there's really no all-encompassing solution. What's the maximum frequency of your signal? And what's the voltage range?
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Mar 28, 2011 07:35
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Slanderer posted:Well, there's really no all-encompassing solution. What's the maximum frequency of your signal? And what's the voltage range? 5v from 1-1000 Hz
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Mar 28, 2011 09:19
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crabrock posted:5v from 1-1000 Hz how much resolution do you think you will need? The ADC ports on most microcontrollers would do fine, but they are usually only 8 bits. If that is all you need, then I would say go with an arduino. It will do the A to D and then send the values down the serial port.
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Mar 28, 2011 10:41
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therunningman posted:I am playing with a very simple comparator circuit and I can't figure out why the TL084 op-amp I am using swings between -2.8 and +6 when it is supplied +/-12V Any reason why you can't use an actual comparator like an LM311? Since op-amps by definition have huge gain, any noise on your inputs could be affecting your output voltage. Are you measuring the output with a scope or a multimeter?
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Mar 28, 2011 15:13
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Hillridge posted:Any reason why you can't use an actual comparator like an LM311? No specific reason, I just happened to have a bunch of TL084's handy. Maybe I have some specific comparator chips hiding somewhere. I am measuring the output with a "DSO Nano" scope. I am going to compare it it with my multimeter too.
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Mar 28, 2011 16:17
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I'm afraid of Electronics. However I have been reading up on Arduino and I want to set up a chasing LED. Similar to the Knight Rider / Cylon examples you see. Are you really limited to a string of no more then 8 lights off an Arduino Uno? How would I do longer strands like say 80 lights?
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Mar 28, 2011 16:18
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therunningman posted:No specific reason, I just happened to have a bunch of TL084's handy. Maybe I have some specific comparator chips hiding somewhere. Is the output a solid 6V/-2.8 or is it real noisy?
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Mar 28, 2011 17:20
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therunningman posted:I am playing with a very simple comparator circuit and I can't figure out why the TL084 op-amp I am using swings between -2.8 and +6 when it is supplied +/-12V Have you checked the power rails to the opamp while you are driving the output? Is your scope set in 50 ohm mode?
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Mar 28, 2011 18:19
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crabrock posted:What's the cheapest option for passing signals into a PC? When I google "analog inputs for PC" I just find really really expensive cards... Are there any cheaper options that are standard or anything? I'm not an expert on electronics by any means - but isn't your soundcard's line in an analogue input? A microcontroller sounds a better solution though.
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Mar 28, 2011 20:05
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Zaxxon posted:how much resolution do you think you will need? The ADC ports on most microcontrollers would do fine, but they are usually only 8 bits. If that is all you need, then I would say go with an arduino. It will do the A to D and then send the values down the serial port. How does something like this work?: http://www.sparkfun.com/products/9832 are all those different channels fed into the PC, or just into the chip? I would like as many analog inputs as I can get. I don't need that fine of a resolution so 8 bit would be fine (I think). I also will have a common ground so I don't need differential channels or anything.
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Mar 28, 2011 22:05
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feedmegin posted:I'm not an expert on electronics by any means - but isn't your soundcard's line in an analogue input? A microcontroller sounds a better solution though. The sound card inputs are AC coupled. But it can be modified.
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Mar 28, 2011 22:14
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crabrock posted:How does something like this work?: Disclaimer - This response is without reading any of the documentation and going off of only this line: Requires digital pins 2,3,4,5 and analog pins 0,1,2 – 48 inputs/outputs for the price of 7 pins! You use 4 digital outputs (16 possible values) to select which analog I/O line gets passed through by each mux. There are 3 muxes, so this gives you access to up to 48 I/O lines, though you can only read 3 at a time, then you need to change your select lines to get a different set of 3.
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Mar 28, 2011 22:27
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I have to come up with an idea for my final project in my electronic communications class. It has to apply to electronic communications in some way, and I have to be able to make it in the next 2 weeks (so no obscure parts probably). I am trying to think up ideas but its hard to be creative when you have to  What would you guys build if you had 2 weeks and a fully-stocked parts closet?
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Mar 29, 2011 00:20
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Three-Phase posted:Skinny, instead of using discrete counters, have you considered buying a microprocessor like the PicAxe microcontroller or a Basic Stamp and doing the counting and stuff in software? Having a single device handle the input, output, and logic would probably be the simplest solution. That was the original plan, but the guy who was going to do it for me is too busy and lives across the country now. That being said, I've done some programming in the past, nothing in Basic or C, but I'm keen to learn. What I'd need to know is what type of hardware I'd need and how to turn a program into a working unit. Basically, what steps do I need to take from here?
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Mar 29, 2011 00:24
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Corla Plankun posted:I have to come up with an idea for my final project in my electronic communications class. It has to apply to electronic communications in some way, and I have to be able to make it in the next 2 weeks (so no obscure parts probably). I would go with a receiving front end at some low frequency (like 133MHz or something), but you'll be pretty limited unless you have a decent network analyzer.
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Mar 29, 2011 00:31
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I can build a communications circuit of some kind, OR I can simulate something in the design program of my choice. I was thinking about simulating some kind of interesting network topology/protocol like multiple-base wireless reception or something.
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Mar 29, 2011 01:13
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Corla Plankun posted:I have to come up with an idea for my final project in my electronic communications class. It has to apply to electronic communications in some way, and I have to be able to make it in the next 2 weeks (so no obscure parts probably). Inject audio into the 60Hz line voltage and read it from across the room with nothing a wall socket Nystral posted:I'm afraid of Electronics. However I have been reading up on Arduino and I want to set up a chasing LED. Similar to the Knight Rider / Cylon examples you see. Are you really limited to a string of no more then 8 lights off an Arduino Uno? How would I do longer strands like say 80 lights? Look into SPI on the Arduino and use that with a shift register chip. ante fucked around with this message at 01:36 on Mar 29, 2011 |
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Mar 29, 2011 01:19
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Hillridge posted:Is the output a solid 6V/-2.8 or is it real noisy? My noticed my multimeter and scope are showing readings differing of about 0.5V. I should probably look into that first. drat.
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Mar 29, 2011 01:25
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Corla Plankun posted:I can build a communications circuit of some kind, OR I can simulate something in the design program of my choice. I was thinking about simulating some kind of interesting network topology/protocol like multiple-base wireless reception or something. Use a sound card to play out a low bandwidth QAM/CDMA/DSSS/etc. signal and receive it with a microphone and demodulate. You could set up a full com link at audio frequencies!
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Mar 29, 2011 01:27
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SnoPuppy posted:Use a sound card to play out a low bandwidth QAM/CDMA/DSSS/etc. signal and receive it with a microphone and demodulate. You could set up a full com link at audio frequencies! This is a pretty good idea, if only because you don't need to do anything in real time for the project. Record a message using your favorite modulation scheme, and have a script to demodulate recorded audio. You could have a clean (generated) signal, a dirty (recorded) signal, and the demodulation script. Just enough to get it done in two loving weeks while still being pretty goddamn cool.
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Mar 29, 2011 01:41
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Corla Plankun posted:I have to come up with an idea for my final project in my electronic communications class. It has to apply to electronic communications in some way, and I have to be able to make it in the next 2 weeks (so no obscure parts probably). I just signed up for an awesome 5 day long Arduino class at a local community workshop, but it's really focused on creating a piece of artwork. I'm not sure what to go for. I'd really like to do something with chiptunes style audio, maybe create a small soundboard with presampled audio clips? Is that too simple?
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Mar 30, 2011 06:28
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I want to sequence 4 automotive relays. Each relay needs to be on for about 15 minutes at a time, and only one relay can be on at once. I want to get this project done before Thursday without paying stupid huge shipping. I live in the sticks, and can't find many parts beyond what Radio Shack carries. Is a 555, a 4-bit shift register, and some basic transistor work going to get this done? I have most of the resistors and basic transistors in a parts box nearby. I might also have a PIC programmer, MSP430 dev board, and chips to fit in it if I REALLY dig and it's REALLY a much MUCH faster solution, including implementing some kind of power supply brick from Radio Shack parts that runs on 12VDC. My budget kinda looks like what you'd have left over if you bought a 6 of Miller Lite instead of a 12 of Shiner Bock.
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Mar 30, 2011 08:17
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babyeatingpsychopath posted:I want to sequence 4 automotive relays. Each relay needs to be on for about 15 minutes at a time, and only one relay can be on at once. I want to get this project done before Thursday without paying stupid huge shipping. I live in the sticks, and can't find many parts beyond what Radio Shack carries. Well, I'm not sure on the sequencing of the relays (is it one relay on for 15 min, then the next on for 15 min, etc..?), but you'll need a bit more. The 555 really, really can't do that kind of period, probably because of a combination of non-ideal capacitor behavior, tiny tiny currents, and other poo poo (as an aside, Linear's new TimerBlox series performs a lot of the same functions that people used the 555 for, but quite a bit better. The LTC6991 timer can go as slow as 9 hours, which is ludicrous). Anyway, without breaking out a microcontroller, I can only imagine reliably getting an ~15 min clock source from some electromechanical timer or time-delay relay, or a whole mess of digital electronics that you can't reasonably build with stuff from radioshack. Aside from the long-period timing source, the rest is straightforward. Bipolar transistors or mosfets to drive the relay (don't forget the inductive spike protection diode across the relay!)
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Mar 30, 2011 09:37
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Corla Plankun posted:I can build a communications circuit of some kind, OR I can simulate something in the design program of my choice. I was thinking about simulating some kind of interesting network topology/protocol like multiple-base wireless reception or something. If it were me, and well being me, I'd go for something like setting up a audio frequency link between two computers using GNU radio and the computers sound cards. Then I'd hook up a noise generator/frequency generator/arb and a competing gnu radio audio source. Then you can use this to demonstrate the effectiveness of various encodings and filters.
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Mar 30, 2011 13:48
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Those are all great ideas, guys. Thank you! I will update y'all with how it all turns out. Cheers 
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Mar 30, 2011 13:54
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I got to do some cool forensics work of sorts the other day. One of my products, among other things, logs certain events related to other equipment. One of these other pieces of equipment had a failure that resulted in a fire which destroyed it and my product along with it since they were in the same housing. This fire was hot enough to de-laminate the PCB and leave the surface traces curled up like the wicked witch's toes. It also melted the solder and left all the surface mount parts scattered on what was left of the PCB. I was able to find the flash chip, extract it from the charred remains of my board, clean it, put it on a working board of the same type, then power the new board and dump the log from the flash to send it to the people whose product had caused the fire. I guess the lesson learned here is that flash chips can take a hell of a lot of abuse and still work. Hillridge fucked around with this message at 15:31 on Mar 30, 2011 |
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Mar 30, 2011 15:28
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babyeatingpsychopath posted:I want to sequence 4 automotive relays. Each relay needs to be on for about 15 minutes at a time, and only one relay can be on at once. I want to get this project done before Thursday without paying stupid huge shipping. I live in the sticks, and can't find many parts beyond what Radio Shack carries. I think this is the kind of project where a microcontroller will work well and will not include a lot of programming. You will just need to set up a timer interrupt, increment a counter, and change state when the count reaches a certain value. I don't know the limits of a 555, but 15 minutes might be too long for the reasons listed by Slanderer. If the 15-minute periods don't need to be exact, it may work -- check datasheets for the limits of component sizes. An alternative might be to use an oscillator, counter(s) and a bit of logic to count up clocks until you hit 15 minutes. I would only bother with this if using the microcontroller is too difficult or you happen to the parts laying around. For the power supply, why not cannibalize a wall wart from something?
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Mar 30, 2011 16:09
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Skinny Bins posted:That was the original plan, but the guy who was going to do it for me is too busy and lives across the country now. I can help you come up with some stuff if you want. Shoot me an email - hillridge@gmail.com
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Mar 30, 2011 16:29
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Ok. Well, I broke out this ice-cream tub of misc parts and found 4xTIP125 (PNP epitaxial darlington transistor), a very meaty rectifier block, ball-bearing 10-turn trim pots from 250-10Meg, some 10-watt .1% resistors, and some misc chips (7408, 7432, lm3900). It looks like I've got a power supply about figured out (voltage divider, my 12V is super-well regulated). I'll use a microcontroller if I can switch these TIP125s directly somehow. They say they'll carry 5A at 60V (65W), and they're in TO-220 packages, so heat sinking should be easy.
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Mar 30, 2011 18:13
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I'm being asked to use an Intel Atom processor to do the job of a microcontroller for political reasons. Anyone know any boards that have an atom on them and have some analog I/O, smaller than 6"x6" or so?
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Mar 31, 2011 23:52
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I haven't seen any Atom eval boards with analog on them, probably because the Atom doesn't have an onboard ADC (AFAIK). In general all of them are complete poo poo for typical microcontroller work because you end up with maybe 10 GPIO and a couple LVDS pins and a bunch of worthless PC interface buses. Best rundown I've seen: http://www.arrownac.com/manufacturers/intel/atom/
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Apr 1, 2011 00:17
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Zenaida posted:I'm being asked to use an Intel Atom processor to do the job of a microcontroller for political reasons. Anyone know any boards that have an atom on them and have some analog I/O, smaller than 6"x6" or so? You're probably going to have a hard time finding an Atom board that has the normal IO associated with a microcontroller (or even an OMAP) since it wasn't really designed for system on a chip applications. Most people want to use them with standard PC peripherals, so I think most boards only support standard ports you'd find on a laptop. If you absolutely have to use an Atom, your best chance is to get a standard board that supports USB and then find a USB IO card that has the analog/digital IO you need. For ultimate irony, you could use an arduino for your IO, connected to the Atom with USB. Also, not sure if this influences the political decision, but this will be a fairly expensive. I imagine $150+ for the Atom board, and then $50+ for the IO even if you only need fairly crappy IO.
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Apr 1, 2011 00:31
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Also Atom chips use a lot more power than a microcontroller so if it's for a battery powered application you'll have a lot of problems. Do the arduino over usb thing!
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Apr 1, 2011 08:14
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Ok. I have this figured out now (I think). I can use the 4000-family CMOS logic chips at 12V just fine. So, I have a 555 with a ~1min period, which is pretty stable, to generate a clock signal for a 4040/4020/4520/4518/4024, which are counters of some flavor. I use some of the top bits (/16 /10 or w/e) to feed a 4028/4514/4515 which are BCD/octal decoders. Feed the decoder outputs through 4069/40106/4502/4041 (or 4049/4069 if nothing else) inverters (inverting buffer, inverting logic level converters) to directly feed the bases of my TIP125 PNP darlington power transistors. I found a guy in town who "has a bunch of chips. Maybe finding the one you need will be... interesting." So I've got some part number alternatives. Do I need current-limiting resistors anywhere? fuses? I'm bolting the transistors to an aluminum plate; that should be OK for heat sinking; they're only going to see 12V@1.25A. http://i51.tinypic.com/25s341f.png
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Apr 1, 2011 09:50
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babyeatingpsychopath posted:Do I need current-limiting resistors anywhere? fuses? I'm bolting the transistors to an aluminum plate; that should be OK for heat sinking; they're only going to see 12V@1.25A. Note that the metal tab on your power transistors may be connected internally (such as to base), so if you're bolting them all to the same aluminium plate, it'll short out your circuit. Edit: You should also have current limiting resistors between the logic outputs and transistor bases. Do B1-B4 represent the relays? If they're PNP transistors/P channel MOSFETs, I think maybe they should be connected straight to VDD with the load between them and ground (the "switching on" event for the P configuration being a voltage difference from the emitter attached to 12V and the base) although I am hardly the master of transistors/analog electronics. Charles Ford fucked around with this message at 16:14 on Apr 1, 2011 |
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Apr 1, 2011 16:03
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babyeatingpsychopath posted:Ok. I have this figured out now (I think). I can use the 4000-family CMOS logic chips at 12V just fine. I feel like that counter is not hooked up right. Have you simulated it? Isn't it going to switch outputs every 8 minutes?
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Apr 1, 2011 16:41
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crabrock posted:What's the cheapest option for passing signals into a PC? When I google "analog inputs for PC" I just find really really expensive cards... Are there any cheaper options that are standard or anything? https://www.fusioncontrolcentre.com
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Apr 1, 2011 17:32
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I just scored a copy of Art of Electronics for $15 bucks. Used, but in "good" condition. Surprised to see a price so low on Amazon marketplace.
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Apr 1, 2011 23:48
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