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211  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Frequently-Used OpAmps? on: June 05, 2007, 03:00:39 pm
Just an update, I've bought a LM324, and got it working in 15 min. Although I think gain of 1000 might be to high, now its so sensitive that I can't even tough the sensor!

Got another question though, what do you do to get resistors to match?

212  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Frequently-Used OpAmps? on: May 28, 2007, 10:47:54 pm
Actually, now I think about it, maybe I'm just complaining too much. The AD7792 has all sorts of settings that let you change the gain, update rate, bias currents and so on that I don't really need to touch, but I just "had to" mess with them because they were there to be messed with! That's what made the code really long. I think if I just left everything in default, it'll be just much simpler. What I was hoping for is a way to get data with something as simple as analogRead(), without adding a large amount of code. Obviously, that's not realistic with external components, and I'm asking for too much. It's a really good quality chip though, almost no noise at 16bit with a gain of 128.

213  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Frequently-Used OpAmps? on: May 27, 2007, 01:12:23 am

Thanks a lot, for the info. I think I'll try the LM324 if I can get a sample of it (No radio shack here in the UK!) . 3.5V should be OK for testing if things are working, the 10bit A/D is not enough anyway. I'm planning to get a 16bit A/D for it eventually.

Perhaps I should start a new thread for Frequently-Used A2Ds. I've got a 16bit AD7792, which works great but is too complicated to interface with. Anyone know a simple to use >16bit A/D that comes in a convenient DIP package?

214  Forum 2005-2010 (read only) / Frequently-Asked Questions / Frequently-Used OpAmps? on: May 25, 2007, 10:42:38 pm

I need some kind of a instrumentation amplifier to get a pressure sensor to output 0-5V. It's basically a Wheatstone bridge with strain gauges. I am at a loss of which OpAmp to use, since there are like millions of them. I need one with a gain of about 500 - 1000, can operate at 5V so I can power it with arduino, and does not need negative voltage. I'm not a EE, I've only ever used OpAmps in one lab at school (the 741), what OpAmps do people usually use in the real world? Where can I get one?

Thanks guys,

215  Forum 2005-2010 (read only) / Bar Sport / Re: servo-servo mechanicals on: February 04, 2009, 12:03:41 pm
I use rubber bands to tie the big horns to another servo when I need to quickly try out some configurations, then hot glue!
216  Forum 2005-2010 (read only) / Bar Sport / Re: Good international electronics shops? on: December 31, 2008, 06:23:22 pm
jds, yeah I also like RC planes  smiley

Asia Engineer (ebay Shop posted by Odisej) also seems pretty good, I've been tempted to buy some stuff from them but have not yet actually bought anything so I can't comment on them...

217  Forum 2005-2010 (read only) / Bar Sport / Re: Good international electronics shops? on: December 27, 2008, 03:01:43 pm
jds, you mean like this: is pretty good, ~1 week shipping to UK.

218  Forum 2005-2010 (read only) / Bar Sport / Re: Freeduino 'Really Barebones' on: December 27, 2008, 03:22:39 pm
I've ordered more than half a dozen of those things from Paul. They all had small transistor-ish regulators. Send him an email if you are worried, sometime he's busy. I don't think this is his full time job...  smiley

219  Forum 2005-2010 (read only) / Bar Sport / Re: To any bored Developer: Smart Fan Controller on: December 01, 2007, 07:29:44 am
Using the interrupt to read fan RPM:

I was thinking about controlling the fan speed with a electronic speed controller for RC airplanes.

220  Forum 2005-2010 (read only) / Bar Sport / Re: 041, over... go ahead 041 over... on: September 07, 2007, 04:27:18 pm
Ah I see...

It must be some coincidence that it was tuned to the police frequency... I thought the police used more sophisticated radios, I guess not.

Thanks for the info!

221  Forum 2005-2010 (read only) / Bar Sport / 041, over... go ahead 041 over... on: September 05, 2007, 06:06:48 pm
Ok, this is weird. So I built a microphone amplifier using the circuit from here:

It works perfectly, except it picks up police radio? WTH is up with that? If you don't believe me, I've recorded a conversation here:

Can anyone explain what's going on? It seems like I only hear the radio if the microphone is attached. And the microphone wire is acting like an antenna, since the audio quality changes if I move it around.

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