AC motor soft start circuit help needed

[zedman2]

Dear All,

I had this soft start circuit before and now I decided to make a similar one for my band saw.
It was tricky to get it out of the synthetic resin I finally managed to figure out the circuit diagram (I hope)
but there's a 8 pin IC which had it's signs sanded down.

Could someone help me what could it be?

I measured around 8.2V DC where I signed it as 9V in the schematic.
R1 is 5W.
I was unable to measure C3 size, it maybe less than 2nF.
I assume D1 is an 1N4001 like diode, and D2 could be a Zener.

Correct me if I am wrong.

thanks,
Zedman

 

[schmitt trigger]

This circuit appears to be very similar to an old Telefunken AC controller.
I believe ST Micro had a similar device

 

[KlausST]

Hi.

Maybe an 8 pin microcontroller.
VCC, GND, ZeroCross, Gate

Klaus

 

[zedman2]

It's not the u208b from Temic, pinout does not match. Unfortunately.

 

[thunderdantheman]

I'll hazard a guess from the Vdd and Vcc locations that it could be a PIC micro controller.. perhaps a 12Fxxx or something...

 

[zedman2]

That's a good idea, will try to connect it to a programmer, but the 8-9V Vcc I measured wouldn't it kill a PIC12?

 

[zedman2]

I suppose it's not a PIC12xx, I tried to read it with PICkit 3 and PICKit 2 but none of them recognize it reads everything as 0s.
Even if it's read protected it should show some non zero bytes after read.

Damn, I tought it'll be an easy task to clone this small circuit...