Nigels programmer

Hi all,
I was just curious, how necessary is that 680 ohm resistor in nigels programmer?

https://www.electro-tech-online.com/custompdfs/2004/12/p16pro40.pdf

There are 2 resistors labeled R9, so I think thats how I missed it. Only bad part is, I already etched and drilled a circuit board for it.

I'm sure I can rig one in there, but I dont

jrz126 said:

Hi all,
I was just curious, how necessary is that 680 ohm resistor in nigels programmer?

https://www.electro-tech-online.com/custompdfs/2004/12/p16pro40-1.pdf

There are 2 resistors labeled R9, so I think thats how I missed it. Only bad part is, I already etched and drilled a circuit board for it.

I'm sure I can rig one in there, but I dont

Click to expand...

First off, it's not 'my' programmer, I added the file because I got tired of repeated requests for it. But it's basically just an improved David Tait design.

The resistor doesn't really look to do a great deal, so it would probably work fine without it - I suspect it's probably just to pull a particular pin to ground, when using the 40 pin ZIF socket.

But it should be easy enough to add the resistor on the back of the PCB anyway, across the back of the socket might be the simpliest place?.

Thats what I was thinking about doing.

and I guess I should have put "The programmer that is linked to on Nigel's site" :lol:

Ok, I have finished the programmer, now I'm working on debugging it...already discovered that I connected my Vin backwards (smoked the 7805 reg.) and had my 7808 and a 3906 swapped. (both the to-92 package)

Now my problem is with my Vpp I think. my 7808 regulator is getting pretty hot. just about too hot to touch. I get an ohm reading of 1.4K between Vpp and ground. (no pic installed). Is this normal?

The output is also up around 16V. What should this voltage be?
and what vpp does the 16f628 need?

I'm going to hook up that 680 ohm resistor and see if that is my problem. (first i have to find one)...

Any suggestions would be greatly appreciated

jrz126 said:

Ok, I have finished the programmer, now I'm working on debugging it...already discovered that I connected my Vin backwards (smoked the 7805 reg.) and had my 7808 and a 3906 swapped. (both the to-92 package)

Now my problem is with my Vpp I think. my 7808 regulator is getting pretty hot. just about too hot to touch. I get an ohm reading of 1.4K between Vpp and ground. (no pic installed). Is this normal?

Click to expand...

I wouldn't have thought so!.

The output is also up around 16V. What should this voltage be?
and what vpp does the 16f628 need?

Click to expand...

Should be 13V.

I'm going to hook up that 680 ohm resistor and see if that is my problem. (first i have to find one)...

Click to expand...

The regulator shouldn't get hot, without the PIC all it's feeding is one LED, and even the PIC takes hardly any current from the Vpp line.

well, I got it to detect my board...but my parrallel port is only putting out 4.27V, is this a problem? It still switches the VPP's and VDD on and off, but is that a high enough level for the clock signal and whatnot?

I think I'm going to try changing my 7808 reg. maybe it is bad as well...
I should have just bought a kit... :x

jrz126 said:

well, I got it to detect my board...but my parrallel port is only putting out 4.27V, is this a problem? It still switches the VPP's and VDD on and off, but is that a high enough level for the clock signal and whatnot?

Click to expand...

It's above TTL level, so should be fine - I can't say I've ever actually measured the levels on the port?.

i built the same programmer that you are building and i also measured the voltages from the parallel port and i remember that the value was quite close to the value you have measured. its not important that it should be exact 5V whats important is that the voltage must be enough to be identified as high and the IC must be working.

Me too built the same programmer.Parallel port voltages were 4.27-4.3V.No problem.The programmer works fine with it.