A 555 timer tutorial

[jjbeamish]

Here is a link to every thing you need to know about the 555 timer.

http://www.uoguelph.ca/~antoon/gadgets/555/555.html

[kevinsatterfield]

thats a nice link but it doesnt actually show ya how to hook a 555 up to a cell to pusle it with....can someone please give a simple guide to how to hook up a 555 based freaquency generator to an elctrolyzer cell?

[nebbian]

Hi,

What you're after is a simple amplifier. There are lots of ways of doing this, the easiest is by using one transistor and one resistor.

Go to find a graphic of how to do this. Use a transistor with a maximum current rating (Ice) of more than what your electrolyser needs. You may need to amplify the signal from the 555 a bit more than with just one transistor, but this should get you started.
In the diagram, the output from the 555 goes in place of Vbb, and your electrolyser goes in place of RL. The current needed for the base is about 1/50 times the current that your electrolyser draws. So if your electrolyser draws 1 amp, then you need 0.02A base current, or 12/0.02 = 600 Ohms for the base resistor.

Alternatively, you can use a FET, which doesn't require a base resistor, and is more efficient. However FETs are a bit more finicky and can blow up a lot more easily if you're not careful. You need to put a high value resistor between gate and source otherwise the FET will fail. Here's a which shows the basics of using a FET.

[kevinsatterfield]

Thank you nebbian for the help but unfortunately it isnt enough for someone like me with little to no xpieirence in electronics.The best i can hope for is to find a circut to copy.Its hard to believe that its being hard to find a simple 555 base circut to pulse a cell with after all this time......Im just looking for a single freaquency pulse to the cell/s to learn a little about it.The freaquebcy generator I have is adjustable but not as much as i would like it to be.Wish i could find one easy to make that has a completely 100% duty cyle adjustability with a freaquencybetween 0 - 20khertz.

[nebbian]

Hi Kevin,

This:

is what you're after.

I'm very surprised that there aren't more circuits like this available in the public domain, initially I thought that you simply hadn't googled enough but after a day of looking I can't find any circuits that will do the job. I even designed a circuit that does 2Hz - 20 KHz with fully adjustable duty cycle and push-pull output before I came across the above link.

[nebbian]

Oops, posted the link to the kit, not the circuit.

The correct link is here:


You may want to put a small piezo speaker and LED on the output so that you can hear what the circuit is doing. Also I'd put in a fine tune on the frequency pot so that it's easier to adjust at high frequencies.

[nobody]

I too have searched all over the net for a pcb circuit such as this. I went to the site and ordered one straight away.

I'm having a friend build a few of the other circuits for me but decided this would be well worth the effort to get a pusing circuit for my coil sooner.

I'm glad to see other HV experimenters here.

[kevinsatterfield]

[nebbian]

[kevinsatterfield]