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Re: Caution on AP-64E EPROM Programmer

Subject: Re: Caution on AP-64E EPROM Programmer
From: Patrick Schaefer <PSchaefer@epost.de>
Date: Sat, 05 Apr 2003 16:32:42 +0200
Newsgroups: comp.sys.apple2
Organization: am Notebook
References: <3e8ae3cc_1@news.iprimus.com.au> <3e8aeb62_1@news.iprimus.com.au> <81Iia.1629$EO.376@fed1read07> <3e8d83a1_1@news.iprimus.com.au> <_esja.40152$7Im.25940@news04.bloor.is.net.cable.rogers.com> <3e8ed76b_1@news.iprimus.com.au>
Xref: archiver1.google.com comp.sys.apple2:29534

Mark Cummings schrieb:

> 1. 27128 & 27256 & 27512 EPROMs use a programming voltage of ~12.5V instead
> of the 21-25V Programming Voltage on most 2716, 2732 & 2764 EPROMs. This
> would be fairly easily achievable on the TL497AC by switching in different
> resistance in the voltage divider on pin 1.

Closing S1-7 connects a Zener diode (D2) to the Vpp line that reduces
Vpp from 25V to 21V (for 2764 chips). You can use the same technique to
get 12,5V.


Patrick

Follow-Ups:
- Re: Caution on AP-64E EPROM Programmer
  - From: "Mark Cummings" <NOTfigjams@primus.com.au>

References:
- Caution on AP-64E EPROM Programmer
  - From: "Mark Cummings" <NOTfigjams@primus.com.au>
- Re: Caution on AP-64E EPROM Programmer
  - From: "Mark Cummings" <figjams@primus.com.au>
- Re: Caution on AP-64E EPROM Programmer
  - From: salfter@salfter.dyndns.org (Scott Alfter)
- Re: Caution on AP-64E EPROM Programmer
  - From: "Mark Cummings" <NOTfigjams@primus.com.au>
- Re: Caution on AP-64E EPROM Programmer
  - From: "Glenn Jones" <rg.jones@rogers.com>
- Re: Caution on AP-64E EPROM Programmer
  - From: "Mark Cummings" <NOTfigjams@primus.com.au>

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