From: Baltissen, GJPAA (Ruud) (ruud.baltissen_at_abp.nl)
Date: 2003-11-03 08:23:06
Hallo Groepaz, > > It is doable but a hell of a job. And not worth the > > trouble IMHO. > > thats why you use a computer for it...it can probe all > possible combinations very quickly :o) I'm sorry for not being that precise; I meant soldering the hardware. > (you may add some electronics to > keep current low on the pins used for probing if in doubt) Unfortunately that is only part of the problem. The Dela tester can test up to 20 pins TTL-ICs. It expects GND on the right bottom pin. Then it has 3 transistors onboard to supply Vcc. Haven't checked it but I guess it only can test 14 16 and 20 pins ICs. To be able to test 4164 DRAMs for example you need a device that can supply GND to pin 16 and +5V to pin 8. A normal TTL output won't do so you need at least two transistors to supply Vss or Vcc for these pins. Better: for all pins. This enables you to test all kind of weird ICs. IIRC there is a TTL serie that has the powersupplies in the middle of the IC. Anyway, you need two signals to steer those transistors plus one to read the pin in case it is an output. Now add the circuitry that enables you to find out if a pin is in- or output. I haven't given it a big thought but IMHO you need at least tw extra signals to steer the analogue part of that circuit. Meaning we end up with a lot of hardware :( Some years ago I started building a 40 pins IC-tester using five 8255's: one 8255 for every 8 pins. The project never ended because I lost it :( That is, I put it somewhere and have no idea at all where. But one of these days I plan a big reorganisation of my room and other places and I hope it will show up. -- ___ / __|__ / / |_/ Groetjes, Ruud \ \__|_\ \___| http://Ruud.C64.org =====DISCLAIMER================================================================= De informatie in dit e-mailbericht is vertrouwelijk en uitsluitend bestemd voor de geadresseerde. Wanneer u dit bericht per abuis ontvangt, verzoeken wij u contact op te nemen met de afzender per kerende e-mail. Verder verzoeken wij u in dat geval dit e-mailbericht te vernietigen en de inhoud ervan aan niemand openbaar te maken. Wij aanvaarden geen aansprakelijkheid voor onjuiste, onvolledige dan wel ontijdige overbrenging van de inhoud van een verzonden e-mailbericht, noch voor daarbij overgebrachte virussen. The information contained in this e-mail is confidential and may be privileged. It may be read, copied and used only by the intended recipient. If you have received it in error, please contact the sender immediately by return e-mail; please delete in this case the e-mail and do not disclose its contents to any person. We don't accept liability for any errors, omissions, delays of receipt or viruses in the contents of this message which arise as a result of e-mail transmission. Message was sent through the cbm-hackers mailing list
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