Author Topic: I need help with a Harmonic Percolator  (Read 729 times)

megatrav

I need help with a Harmonic Percolator
« on: July 19, 2021, 10:23:28 AM »
Hello,

This is my first time posting on this forum.
I am currently working on building a Harmonic Percolator on tagboard. I found the layout online and it has given me quite a bit of trouble.

I have a lot of pictures to include. I have checked the pinouts for the 2N34a and 2N3565.
The issue is, I am either getting no signal when engaged or I am getting a ton of oscillation. Bypass signal working fine.
I have tested the voltages and they are not even close to what they are suppose to be.





I grabbed the best pics I could of the board. You will notice in some of them that the 2N34a has yellow legs. I have already broken the legs off on one of these and had to order another, so I attached some wire so that I wouldn't have to order another.


























Any help would be greatly appreciated. I have no idea what could be causing the issues.

duck_arse

Re: I need help with a Harmonic Percolator
« Reply #1 on: July 19, 2021, 10:48:32 AM »
welcome to the forum. your 47uF should really be tantalum for proper operation. a larger value aluminium electro can stop "octaving", if that is your oscillatings, but the 47uF tant should prevent them.

how come the voltage on the emitters differs? or does it?
"So many things I would have done, but cows got in my way" - Both Sides Now

megatrav

Re: I need help with a Harmonic Percolator
« Reply #2 on: July 19, 2021, 10:54:47 AM »
Okay, so they electrolytic cap I am using could be causing the problem?

The layout shows an electrolytic but I can try a tantalum if that would fix the issue. It is a 47u as the layout says it should be.

megatrav

Re: I need help with a Harmonic Percolator
« Reply #3 on: July 19, 2021, 11:33:09 AM »
Also, I am not sure why the voltages are so weird. I tested them in the circuit while it was powered up and these are the numbers I got.
My multimeter is also auto so maybe I should try my older one and see if it's different

duck_arse

Re: I need help with a Harmonic Percolator
« Reply #4 on: July 20, 2021, 10:57:18 AM »
Quote
Okay, so they electrolytic cap I am using could be causing the problem?

it might be not preventing the problem. I'm sure in one of the threads dissecting the weirditties of the perco, it was stated that the low ESR of tantalums was paramount to the particular topology. can you post the schematic you are working from, save us trying to squint at the values on your layout diagram? then we might dissect your expected voltages.
"So many things I would have done, but cows got in my way" - Both Sides Now