Hi Folks,

As a hobby I do a lot of etching and electroplating using a basic DC supply. I am at the point now where I need a lot more control of the process.

The professional plating shops are now using PED (pulse electro-deposition).

"This process involves the swift alternating of the potential or current between two different values resulting in a series of pulses of equal amplitude, duration and polarity, separated by zero current. By changing the pulse amplitude and width, it is possible to change the deposited film's composition and thickness".

Perfect! The only snag is the machines that are available are far too big for what I need, big commercial set ups costing thousands. I am only working relatively small items so an output up to 5 amps will be more than enough.

· Variable pulse width.

· Variable duty cycle.

· Variable amplitude


I have come across the circuit below and was wondering if anyone could assist in suggesting any alternatives or different approaches.

Regards

Mark

 

Your circuit might function as a modulating signal to a power transistor. ... Need to try it out on ltspice or something similar.

 

There is at least one problem with that circuit. There is no dc path to the LT1057 pin 6. I don't understand what that amp is supposed to do.

 

Hi,

I have designed a circuit for just this as I do electroplating too. In my opinion, the reverse pulse technique is overkill for simple projects, you need to look into better plating chemistry instead (for a professional finish).

All the best,
Robin

 

Hi Folks,

As a hobby I do a lot of etching and electroplating using a basic DC supply. I am at the point now where I need a lot more control of the process.

The professional plating shops are now using PED (pulse electro-deposition).

"This process involves the swift alternating of the potential or current between two different values resulting in a series of pulses of equal amplitude, duration and polarity, separated by zero current. By changing the pulse amplitude and width, it is possible to change the deposited film's composition and thickness".

Perfect! The only snag is the machines that are available are far too big for what I need, big commercial set ups costing thousands. I am only working relatively small items so an output up to 5 amps will be more than enough.

· Variable pulse width.

· Variable duty cycle.

· Variable amplitude


I have come across the circuit below and was wondering if anyone could assist in suggesting any alternatives or different approaches.

Regards

Mark

Interesting.....
Looking at the circuit it looks like you could vary :
Frequency
Duty cycle
Amplitude
Do you want/need all three?
Is your power supply voltage adjustable? What voltage?
If so you can eliminate the op amps and just adjust the supply.

 

That LT1057 op amp with the diode is a logarithmic amplifier. See section 7.7 here:
https://wiki.analog.com/university/courses/electronics/text/chapter-7

 

That LT1057 op amp with the diode is a logarithmic amplifier. See section 7.7 here:
https://wiki.analog.com/university/courses/electronics/text/chapter-7

I meant the one with pins 5/6 as inputs, I think it is IC2A (difficult to read diagram). No DC path to pin 6.