Lloyd Gordon wrote:
Pin 32 definitely connects to the regulated 5V+ from the 7805. The trimpot does just regulate the LM317. I added bypass capacitors for all the IC's which are recommended. I also modified it slightly adding an extra dipswitch so it will program the 27C080 1 mbyte EPROM's. I hope you are using a ZIF EPROM socket, they are really cheap from Futurlec. Let me know if you have problems. By the way, I run mine by booting right to Win98 DOS and use a really old Pentium 90 with a bidirectional parallel port.
Hi, Lloyd Gordon! Thank you very much for your support. I've tried to contact zws and Mike Gordon (from the 27C801 mod) without success.
1 - Just like I was thinking: the trimpot regulates only the LM317. But... I used a 12Vcc plugpack and my voltage measures stands for:
a ) 5Vcc in each 4040 (normal)
b ) no voltage at EPROM socket (because in the original ZWS project there's no connection for pin32, different from Mike Gordon Project).
c ) - The trimpot
isn't changing the LM317 voltage, although the voltage at DB25 pin16 (init) is normal, I think (~5Vcc). Does voltage change occurs
only with the EPROM burner connected to the parallel port? I'm using a vertical trimpot, and my connections are:
Is this right?
2 - I didn't use the 240ohms resistor, since I'm unable to find this measure
So, I'm using a 270ohms instead. I think there's no problem...
3 - So, what do you think about the LM317 voltage? Does my trimpot is wired correctly?
4 - And.... if you connect the pin 32 to 5Vcc, How can the programmer burn/read 27C256, witch has 28 pins?
My initial tests where done
without connect to the parallel port, because I must make the cable first. Btw, I've included all the capacitors mentioned by Mike Gordon mod.
Sorry for bother you, but I'm very confident cool about this project.
Cheers