Page 3 of 18
Re: ZX81 rebuild
Posted: Sat Oct 07, 2017 10:25 am
by 1024MAK
More about transistor switch off times.
The bits in the datasheet that you are looking for are:
- Max. Storage time (ts or tstg)
- Max. Turn-off time (toff)
Both meaured in nanoseconds (ns).
Links to the datasheets here:
http://hardware.speccy.org/datasheet/ztx313.pdf
https://www.onsemi.com/pub/Collateral/BC182-D.PDF
As you can see, the BC182 datasheet does not even list the storage or turn off times...
Mark
Re: ZX81 rebuild
Posted: Sat Oct 07, 2017 11:30 am
by 1024MAK
Although I don't have a plastic cased through-hole transistor to recommend, a 2N2369 or 2N2369A should work. There was a plastic version PN2369A but this is harder to find/buy. They are also not cheap compared to most plastic transistors in TO92 packages.
Mark
Re: ZX81 rebuild
Posted: Sat Oct 07, 2017 12:08 pm
by Lardo Boffin
Thanks Mark.
I did find some new old stock on ZTX313’s eBay but they are somewhat lacking in detail...
https://m.ebay.co.uk/itm/QTY-10-ZTX-313 ... Ciid%253A1
Re: ZX81 rebuild
Posted: Sat Oct 07, 2017 10:27 pm
by gammaray
Just a note. Ferranti does not manufacture a PNP complement to the ZTX313 for use in a "WHYWAIT" circuit. That I could find anyway.
Personally, I love the ZXmore and ZXblast and modifying a Zeddy-bear but would like to see a new OEM-style ZX81 PCB V.4 made that includes some of these transparent add-ons like the signal enhancer for tape play, whywait and maybe 2000-4000 RAM/ROM (FLASHROM) selectable on-board memory configuration,50hz or 60Hz, ...
I got to get busy!
Re: ZX81 rebuild
Posted: Sun Oct 08, 2017 3:24 am
by axtelle
Re: ZX81 rebuild
Posted: Sun Oct 08, 2017 4:45 am
by gozzo
sacré merde..£17.80..
i wish i'd bought a load at 50p each when i had the chance ...d'ohh!!
Re: ZX81 rebuild
Posted: Sun Oct 08, 2017 4:46 am
by gozzo
oh, and 2N2369 plastic version... MPS2369 ...i have at least one zx81 that has these in...
Re: ZX81 rebuild
Posted: Sun Oct 08, 2017 7:44 am
by 1024MAK
gozzo wrote: ↑Sun Oct 08, 2017 4:46 am
oh, and 2N2369 plastic version... MPS2369 ...i have at least one zx81 that has these in...
Yep, but in my search yesterday these were even harder to find...
Mark
Re: ZX81 rebuild
Posted: Sun Oct 08, 2017 9:26 am
by Lardo Boffin
1024MAK wrote: ↑Sun Oct 08, 2017 7:44 am
gozzo wrote: ↑Sun Oct 08, 2017 4:46 am
oh, and 2N2369 plastic version... MPS2369 ...i have at least one zx81 that has these in...
Yep, but in my search yesterday theses were even harder to find...
Mark
I have just bought 5 MPS2369 (
https://m.ebay.co.uk/itm/MPS2369-Transi ... Ciid%253A1) new old stock from eBay. I don’t really like buying components from there but sometimes...
Re: ZX81 rebuild
Posted: Sun Oct 08, 2017 11:34 am
by 1024MAK
Yeah, note that I was only searching RS, Farnell, Rapid, ESR, Bowood, Mouser etc...
I normally only use eBay for semiconductors and some other electronic parts if said parts are unavailable from normal electronic suppliers / businesses.
Although some eBay sellers are proper honest businesses and do supply genuine parts.
So far, the only fake parts that I have received (as far as I know) are:
- EEPROM chips (won't "burn", all address locations just read as 0xFF) [more info on StarDot],
- a 65C02 (which tests as a NMOS 6502, NOT a CMOS 65C02, and this is from a UK based seller),
- and some SRAM chips, which all have different moulding marks/stamps, but all have the exact same screen printing, but they all work in a ZX80.
I also have some other CPUs, and it's possible that some of these are fake or more likely are 'pulls'. The most common issue with cheap chips from overseas, is that they are sold as 'new', but are actually used 'pulls' that have been cleaned up and the pins re-tinned. I don't mind if they are honest in the listing, but some either don't say, or they are listed a 'new'
Oh, and I'm not including chips that I bought knowing that they are 'pulls' (and work fine) in the list above.
Mark