Pictures of my ZX81 fitted with a RECOM 5V Regulator

Discussions about Sinclair ZX80 and ZX81 Hardware
Lardo Boffin
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Re: Pictures of my ZX81 fitted with a RECOM 5V Regulator

Post by Lardo Boffin » Mon May 21, 2018 4:45 pm

Try this MuRata one - it is 1.5a

https://www.retroleum.co.uk/spectrum-128-modifications

I have bought a bunch of stuff off this site.

As I understand it the toastrack sucks up most of the output of the original regulator so if you run it with anything plugged in it is not good.
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
Iss 3 ZXVid
TS 1000 iss 3, ZXPand AY, ZX8-CCB, ZX-KDLX & ChromaSCART
TS 1500
TS 2000
Spectrum 16k (iss 1 s/n 1499)
Various Spectrum 48ks plus a DIVMMC future and SPECTRA

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1024MAK
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Location: Looking forward to summer in Somerset, UK...

Re: Pictures of my ZX81 fitted with a RECOM 5V Regulator

Post by 1024MAK » Mon May 21, 2018 7:37 pm

1.5A and 2A types are available from the large electronic companies. For example, RS components in the U.K. have some (link to listings of Recom types).

Mark

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adonet
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Re: Pictures of my ZX81 fitted with a RECOM 5V Regulator

Post by adonet » Wed May 23, 2018 9:11 pm

I found this one for ZX Spectrum 128K for sale in Holland:
https://www.conrad.nl/p/tracopower-tsr- ... -x-1511338
traco2.jpg
traco2.jpg (19.75 KiB) Viewed 1942 times
and this one for ZX Spectrum 48K and ZX Spectrum + 48K and ZX 81
https://www.conrad.nl/p/tracopower-tsr- ... 1-x-156673
and in UK
https://www.conrad-electronic.co.uk/ce/ ... archDetail
traco1.jpg
traco1.jpg (17.55 KiB) Viewed 1942 times
I have been ZX computing since 1981, Zx81, 16Krampack, ZX Spectrum 48, Alphacom32, ZX Spectrum +, Lo>>profile keyboard, ZX Spectrum 128K
Ubuntu 18.04 and Raspberry PI

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gammaray
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Re: Pictures of my ZX81 fitted with a RECOM 5V Regulator

Post by gammaray » Fri May 25, 2018 10:26 pm

Mandatory equipment in my mind. Makes room for fan and minimizes power rejection causing heat. I used a uncased 'Chiner' model mounted at right angle.

https://www.sinclairzxworld.com/viewtop ... 036#p20770
5-TS1000,UK ZX81<-Sheelagh, US ZX81, 2-TS1500/KDLX , 3-TS2040 printer, 2-TS2020 cassette decks, ZXPAND+AY, ZeddyNET, ZXBlast, UDG, ZX8CCB, AERCO, BUILDS/REPAIRS ZX Spectrum, ZX80 Minstrel, ZXMAX48 v1 v2, 2-TS-2068, ROM, 16kRAM

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adonet
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Re: Pictures of my ZX81 fitted with a RECOM 5V Regulator

Post by adonet » Fri May 25, 2018 10:54 pm

Now it looks like this. The colour of the regulator is Both black instead of rose, but they are the same. 1amp for the zx81 and ZX. Spectrum. 2 amp for the zx spectrum 128k.

And they stay cool.
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IMG_20180525_132019.jpg
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I have been ZX computing since 1981, Zx81, 16Krampack, ZX Spectrum 48, Alphacom32, ZX Spectrum +, Lo>>profile keyboard, ZX Spectrum 128K
Ubuntu 18.04 and Raspberry PI

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gammaray
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Re: Pictures of my ZX81 fitted with a RECOM 5V Regulator

Post by gammaray » Fri May 25, 2018 11:10 pm

I just got a refurbed Spectrum from the Netherlands and intend to convert to NTSC with that version of the ULA and the right oscillators.

I'll need to change regulator as well. The heatsink seems to be 3 times the surface area as the TZX81000 heatsink but only twice the current.

Strange the ULA did not have provision for both markets like the ZX81 but I guess the change in oscillators prevented that.

Addendum:
I had bought a larger heatsink 30 years ago for ZX but I am not sure it lowered the overall case temperature given physics Andy's prior comments mention elsewhere. If anything it just delayed time it took to start reach
Last edited by gammaray on Sat May 26, 2018 2:28 am, edited 1 time in total.
5-TS1000,UK ZX81<-Sheelagh, US ZX81, 2-TS1500/KDLX , 3-TS2040 printer, 2-TS2020 cassette decks, ZXPAND+AY, ZeddyNET, ZXBlast, UDG, ZX8CCB, AERCO, BUILDS/REPAIRS ZX Spectrum, ZX80 Minstrel, ZXMAX48 v1 v2, 2-TS-2068, ROM, 16kRAM

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1024MAK
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Re: Pictures of my ZX81 fitted with a RECOM 5V Regulator

Post by 1024MAK » Sat May 26, 2018 1:37 am

Drifting way off topic here :shock:
The ZX Spectrum ULA picture circuitry is far more complex than the ZX81 ULA circuitry, and as Sinclair had a time limit and a limit on the number of gates in the first generation of ULA chips for the ZX Spectrum, it was not really practical to include the extra circuitry to support both TV standards in the same chip.

Mark

Lardo Boffin
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Re: Pictures of my ZX81 fitted with a RECOM 5V Regulator

Post by Lardo Boffin » Fri Oct 26, 2018 11:31 pm

1024MAK wrote:
Fri Dec 16, 2016 5:53 pm
Here are some pictures of an issue 1 board ZX81, where I removed the 7805 series voltage regulator and replaced it with a RECOM R-785.0-1.0 switching regulator.

I also fitted two extra 100nF ceramic capacitors (marked "104").

I had originally intended on mounting the RECOM regulator vertical. But that did not work for me, so instead used some tinned solid core wire to make extra long legs at a right angle (90 degrees) so that I could lay the RECOM regulator horizontaly on it's back.

The first 100nF capacitor goes in the two holes in the PCB next to the 3.5mm jack socket for the 9V power input.

The second 100nF capacitor simply goes in two of the three the spare holes on the edge of the board where a switch can be fitted (provision for a channel / frequently band change switch for modulators that support this).

These holes may already be filled with solder. If this is the case, remove the solder with a solder sucker or desolder braid.

I decided to add these extra capacitors for two reasons, first the RECOM regulator is designed to be a straightforward replacement for the conventional 7805 series regulator chips. And having capacitors close to these is recommended to improve stability. This is good practice with any regulator. And secondly, they will help reduce electrical noise on the power lines.

I used thin heatshrink tubing on one capacitor. But this is not nessassary. If you want, you can also heatshrink the wires and legs on the RECOM regulator.

To make the extra leads for the RECOM regulator, I used stripped wires from some solid core telecom or ethernet cable that I had spare. I used a small set of round nose pliers to form a spiral ring on the end, so that it would slip over the leg of the RECOM regulator. Then I soldered it in place.

Note that when soldering the extended legs of the RECOM regulator to the PCB, enough heat may travel up the wire and melt the solder holding the wire to the leg of the RECOM regulator. So use something to hold the regulator in place while doing the soldering.

IMG_3449.JPGIMG_3450.JPGIMG_3451.JPGIMG_3452.JPGIMG_3453.JPG

Mark
I have just noticed the extra capacitors (100nF) being fitted to help stabilise the RECOM. Does doing this make much difference? Is it about stability or reduced heat generation?

What is the spec of these? Would something like this do? https://cpc.farnell.com/multicomp/mcrr5 ... capacitors

And finally, is it the same placement on an issue one and three board?

Thanks!
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
Iss 3 ZXVid
TS 1000 iss 3, ZXPand AY, ZX8-CCB, ZX-KDLX & ChromaSCART
TS 1500
TS 2000
Spectrum 16k (iss 1 s/n 1499)
Various Spectrum 48ks plus a DIVMMC future and SPECTRA

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gammaray
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Re: Pictures of my ZX81 fitted with a RECOM 5V Regulator

Post by gammaray » Sat Oct 27, 2018 1:14 am

Lardo Boffin wrote:
Fri Oct 26, 2018 11:31 pm
1024MAK wrote:
Fri Dec 16, 2016 5:53 pm
...
And finally, is it the same placement on an issue one and three board?

Thanks!
Yes on ZX81 and TS1000 boards have regulator in the same spot. Spectrum is of course different.

Charles
Last edited by 1024MAK on Sat Oct 27, 2018 4:10 pm, edited 1 time in total.
Reason: Fix quote
5-TS1000,UK ZX81<-Sheelagh, US ZX81, 2-TS1500/KDLX , 3-TS2040 printer, 2-TS2020 cassette decks, ZXPAND+AY, ZeddyNET, ZXBlast, UDG, ZX8CCB, AERCO, BUILDS/REPAIRS ZX Spectrum, ZX80 Minstrel, ZXMAX48 v1 v2, 2-TS-2068, ROM, 16kRAM

Lardo Boffin
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Joined: Sat Nov 26, 2016 2:42 am

Re: Pictures of my ZX81 fitted with a RECOM 5V Regulator

Post by Lardo Boffin » Sat Oct 27, 2018 7:28 am

gammaray wrote:
Sat Oct 27, 2018 1:14 am
Lardo Boffin wrote:
Fri Oct 26, 2018 11:31 pm
1024MAK wrote:
Fri Dec 16, 2016 5:53 pm
...
And finally, is it the same placement on an issue one and three board?

Thanks!
Yes on ZX81 and TS1000 boards have regulator in the same spot. Spectrum is of course different.

Charles
Thanks but I meant the placement of the extra capacitors. :D
Last edited by 1024MAK on Sat Oct 27, 2018 4:11 pm, edited 1 time in total.
Reason: Fix quote
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
Iss 3 ZXVid
TS 1000 iss 3, ZXPand AY, ZX8-CCB, ZX-KDLX & ChromaSCART
TS 1500
TS 2000
Spectrum 16k (iss 1 s/n 1499)
Various Spectrum 48ks plus a DIVMMC future and SPECTRA

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