How to build a DC->AC converter using resistors capacitors and diodes (no inductors)

[aeftimia]

How to build a DC-->AC converter using resistors capacitors and diodes (no inductors)

I have been trying to learn electronics (I am familiar with the principles, just have no experience designing complex circuits to fulfill purposes), so I went to RadioShack, got myself:

breadboard
assorted TO-92 transistors (pnp and npn)
resistors
diodes
capacitors
LEDs
D-battery holder (so my power source is 2 D batteries in series--1.5V each, 3V total)

They did not have inductors. I have been trying to make a DC-AC converter for a few days and I finally give up. I just cannot understand some of the diagrams on the wikipedia article on inverters.

I really do not care what frequency it oscillates at at this point (although slow enough that I could see a light flicker would be nice) or what waveform comes out (I would prefer a sine wave, but I recall being able to smooth out a square wave with a capacitor.)

Could someone recommend a simple design using my equally simple components. Or if the only way to do it is with some complicated design--please explain how it works.

Thank you

 

[MisterX]

I think that if you are trying to learn electronics with little training, knowledge, or experience in that area, a power electronics project might not be an ideal first project.

Perhaps building a simple digital logic circuit, a multistage amplifier, or a radio or infrared receiver would be a better choice.

 

[Bobbywhy]

aeftimia, You might make a free-running multivibrator. You control its on/off time (frequency) with different resistors and capacitors. It generates a square wave. Then you could filter that with a capacitance/resistance network to get a smoother wave. Except it may not output enough power to drive a led. So you would have to amplify that signal to drive your load. Use Google and Wiki for these basic circuits. Good experimenting.

 

[jim hardy]

I'd advise you to get a few 555 or 556 timers.

They are a versatile block with good drive capacity and will happily drive small lamps or LED's.

and lots of hobbyist information out there.

start googling 555 hobbyist

i used to frequent a forum called discovercircuits.com
lots of beginners ask questions there there
and the folks are helpful
see a thread called "stereo" by danud
you might want to build yourself a hifi instead.

 

[yungman]

I know you can make a multi-vibrator with two NPN or PNP transistors. I don't remember the exact circuit, it is hooked up like a differential pair with the collector of one transistor feedback to the base of the other transistor ( it is positive feedback) through a resistor with the cap to ground or something like that. That is to form a delay and use for setting the frequency of toggling. Someone should know what I am talking about and have the correct circuit.

Read up 555 and buy a book on project using 555 is a very good idea also. I actually design and build a burglar alarm using 555 and used in my own car...I actually used 556, the dual version of 555.

 

[aeftimia]

Thank you. After some time studying the circuit (and watching it with Falstad's impressive circuit simulator) I have a working astable multivibrator. That is perfect. I will work on changing the waveform next.

Thanks again!