Sinclair ZX80 / ZX81 / Z88 Forums

Do it. Put that ULA heatsink on...

But also replace 7805 regulator with a new TRACO or equivalent switching regulator so you can remove the 7805 heatsink...

And put an old DC brushless fan motor from 486 PC era to force air out the slots where the regulator use to be. Tack it to the shell some how.. epoxy..
Can be run from the 9 to 12 V DC transformer input. Make sure it point out to draw air out of case shell.

You can also set up a separate switching regulator for the fan so that it's performance is constant. You can go from 9 -> 12 VDC if you pick the right one and adjust it properly.

^Siggi points to a 5V on Ebay but I prefer to rummage through rusted cases of old PCs for fans that once installed only last for two weeks. Gotta economize you know!^

Any naysayers?

Electrostatic problems, radio frequency interference... anything?

I was wondering where the room would be for the ZX81 board after a fan had been fitted in the case....

Mark

Take this one:

http://www.ebay.de/itm/2pcs-Mini-2507-2 ... 0677.m4598

Once you have added a fan there will be noise coming out of your Zeddy.
Time to consider a little board to control the speed of the fan in order to change the frequency of the noise. Next would be have it playing tunes that match the game you are running. Some kind of ambi-sound (to match the used Ambilight TV from Philips)
I had a program on my Atari ST that played music by controlling the track stepper motor of the floppy. I remember "Wenn bei Capri die rote Sonne im Meer versinkt"

Or you could try just using it.

As someone much wiser than me on this forum said, the heat from these chips is hardly argon arc furnace temperature and are not as fragile as you may think. Every knackered ULA I've come across in thirty odd years of using them as been damage caused by things such as plugging/unplugging interfaces whilst powered up or in my case plugging in the ULA itself whilst powered up. , I've yet to meet anyone who can show me one provably damaged by excess heat.

Just for reference I have two zeddies in my studio which I have used for music creation since 2011, one cased one uncased.They are used at least five days a week never less than three for up to six hours at a stretch (the joys of retirement) I have three more that when in use run up to a week at a time working on large numbers for use in ciphers/codes (a passion of mine) and no failed ULA's through heat damage yet. I suspect most of you use them for a slightly lesser time period so no worries there I would have thought.

I also have one which, thanks to Sir Morris, will soon be heavily hammered as a text to speech via USB device, and a melted chip is the least of my worries.

The internal fan thing Yes great but don't forget to cut some nice big slots out of the case near/over the ULA so as to draw a nice draught of cooling air over the chip.

At the end of the day each to his own and do what you feel is right for you or you could, as they say across the water, have a Coke and a smile and just enjoy using your 81 rather than worrying about the fragility of its internals real or perceived and I speak as a user/thrasher of zeddies not a collector, I use them hard and far beyond what they were designed for whereas most of you I'm guessing give it the odd whirl around the block for half an hour or a game or two here and there then call it a day so why worry there are plenty more of them out there they ain't Rembrants.

I was wondering where the room would be for the ZX81 board after a fan had been fitted in the case....

With the regulator heatsink gone, there is space right above "vent hole" where it use to be. Zeddy-board does not extend to edges of case, just the top half.

The fan does not have to be a F5 tornado, just pull air from back and gaps in ear/mic holes and force out bottom or vice versa.

siggi wrote: ↑Sat Sep 30, 2017 8:24 pm

mhudson52 wrote: ↑Fri Sep 29, 2017 6:38 pm Now would be a good time to put a good heat sink ...

Oh Oh, he wrote the forbidden word
Over to Moggy (and his dog)

Siggi

Uncle! Uncle! I surrender! (tapping out on mat)

mhudson52 wrote: ↑Sun Oct 01, 2017 5:31 pm

siggi wrote: ↑Sat Sep 30, 2017 8:24 pm

mhudson52 wrote: ↑Fri Sep 29, 2017 6:38 pm Now would be a good time to put a good heat sink ...

Oh Oh, he wrote the forbidden word
Over to Moggy (and his dog)

Siggi

Uncle! Uncle! I surrender! (tapping out on mat)

classy.

Best laugh I've had all week,

gammaray wrote: ↑Sun Oct 01, 2017 4:02 pm

I was wondering where the room would be for the ZX81 board after a fan had been fitted in the case....

With the regulator heatsink gone, there is space right above "vent hole" where it use to be. Zeddy-board does not extend to edges of case, just the top half.

The fan does not have to be a F5 tornado, just pull air from back and gaps in ear/mic holes and force out bottom or vice versa.

Joking aside,Gammaray, the micro fan idea does have merit and the fans that Siggi illustrates will probably work quite well in tandem with the switching regulator and I can say from my experience in building fan cooled heat sink solutions for audio amplification that it doesn't require massive amounts of air movement to provide adequate cooling.


Hmmm I feel a new project coming on.

Just theoretical mind you , a heatsink, ULA or other, in an enclosed or restricted space WILL lower the peak temperature in the chip lowering thermal stress but NOT lower the temperature in the space. i.e. Both camps are correct.

(Running out the door to get in the car to avoid the Moggy-lash )