Re: pulse generator

Hy Denis,

I, too opt for the NE555 circuit. You need some kind of rectified and filtered power supply, a transformer wall wart with 9-12 Volts would be good. I prefer those over switchers which are often specially tailored for given loads like cell phones. You can easily find out if it´s a transformer type, just pick it up, they are heavy. And you have one around the house from an old scanner, a toy or god knows what else for sure.

The 555 is connected as an astable multivibrator (big words, just google it), means it retriggers itself all the time. You need a rheostat and a fitting cap. The resistance fills the cap over time and at a certain level, then triggers the output signal from low to high. Higher resistance or bigger cap means lower frequency. don´t hesitate to buy a few more 555s, solder coloured cables to the legs of one and begin to play around. You can´t solder the cables to death, while you play around. This could happen to the 555 when you heat it up often or over excessive time.
Also, buy a 7805, this is a three terminal voltage regulator, as cheap as the LM555 which should cost 0,20$ . You can fuel it with any mean looking and humming source up to 35 volts, it will spit out a clean, hum free 5V up to 1A of load current(with proper heat sink). Three legs, input, ground, 5 Volts out.
Run the Ne555 from it, also attach wires or a terminal to the 5 volts so you can attach a few wires there because you will usually need 5V at a pin to enable the drive and another 5volts/ground level to tell the driver which way to turn.
The 5 Volt is the logic signals max. voltage and is used with a computers parallel port and also the usb port.
In case you need help with the circuit or with the voltage regulation, feel free to contact me.

Search words for google would be square wave generator.

Cheers,
Johann