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Noob needs a little help

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#57175

Noob needs a little help | 4 November, 2008

This is my first circuit board that I am attempting to build and need a little help. Not exactly sure what is going on but maybe one of you guys could give some input. I am attaching the electrical diagram I am using. Everything thing seems to be working fine besides one thing. When I hook the positive and negative to my 12v supply D1 lights up and D2 blinks every 3.3 seconds and should have an output of 0V-.09V. When I put the positive side of my volt meter on the output and the negative side of the volt meter on my negative post I get nothing. The only time I get any reading is if I touch the negative side of the volt meter with the opposite hand I am holding the output wire on the positive side of the volt meter. Doesn't make sense to me since I have one side of R4 running to the output and on the other side it is running to the negative side of D2. Here are the component values. R1 100 K Ohm R2 1 M Ohm R3 100 K Ohm R4 10 K Ohm C1 4.7 uF C2 22 uF D1 1.7v@20mA LED D2 1.7v@20mA LED Any suggestions asap would be very much appreciated. Thank You

Attachments:

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#57187

Noob needs a little help | 6 November, 2008

I would rethink your schematic. If you are using D1 for power indication, put D1 in series with a 1KO resistor to ground. D1 will 1.5-2.2V which will your supplies voltage to your 555 timer. What are you driving on the ouput at pin 3? If you are using D2 to indicate the status of the output, take R3 and D2 in series to ground and take the ouput directly from pin 3. You will need to work out these kinks in your circuit before judging if you have a problem or not. The best site for electronics questions is

http://www.electro-tech-online.com

There are many experts here waiting and wanting to assist others. Just go to the "General Electronics Chat" forum and post your question there.

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#57188

Noob needs a little help | 6 November, 2008

Thanks, I am extremely new to this, in fact it's my first board that I am attempting to put together. I just needed an out put that pulsed between 0v-.09v. I am using it for an oxygen sensor simulator and found this diagram. I will try that site that you suggested, I appreciate it.

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#57318

Noob needs a little help | 18 November, 2008

Jeez, didn't you go to DeVry?

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