Lambda power supply

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bodz
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Lambda power supply

Post by bodz » Sat Jul 27, 2019 10:02 pm

I managed to grab a Lambda 8300 a couple of weeks ago, but it didnt come with a power supply... just wondering what the voltage and amperage are for it?

Also .. how easy is it to find a 16 or 32k memory expansion for it?

Any help welcome :)

thanks :)

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mrtinb
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Re: Lambda power supply

Post by mrtinb » Sat Jul 27, 2019 10:39 pm

I use a standard multi voltage power supply you can get anywhere. These have different power sockets. I have set it for 9V and 5V in the middle.

Regarding the RAM, I use a standard ZX81 16K RAMpack.
Martin
ZX81, Lambda 8300, Commodore 64, Mac G4 Cube

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1024MAK
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Re: Lambda power supply

Post by 1024MAK » Sun Jul 28, 2019 12:01 am

bodz wrote:
Sat Jul 27, 2019 10:02 pm
I managed to grab a Lambda 8300 a couple of weeks ago, but it didnt come with a power supply... just wondering what the voltage and amperage are for it?

Also .. how easy is it to find a 16 or 32k memory expansion for it?

Any help welcome :)

thanks :)
See my post from some years ago regarding power supply voltages for a Lambda 8300.

Mark

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mrtinb
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Re: Lambda power supply

Post by mrtinb » Sun Jul 28, 2019 11:07 am

There is no mention of the volt on either the case or in the manual.

I usually start at 6V and add 1.5V in steps until it works fine. When there's no expansions the low values work great, but when I add RAMpack and Colour Pack more juice is needed.

However the German book 'Das PC 8300 ROM-Buch' states (translated):
The housing of the power supply is small and gets quite warm. The connection pins do not correspond to the German standard. Therefore one must connect an intermediate plug or use another power supply.

The voltage of the power supply is very high

Open circuit voltage 15.8 - 16.9 V
Operating voltage 13.6 - 14.5 V

The regulator has to burn this down to 5 volts, so destroy 9 volts. It is in the computer that I have here, about 50 degrees (celcius) warm with closed housing. If additional components are plugged in at the computer, they remove power from the internal power supply of the computer (i.e. do not have their own power supply unit). So you can overload the regulator of the computer with it.
Martin
ZX81, Lambda 8300, Commodore 64, Mac G4 Cube

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1024MAK
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Re: Lambda power supply

Post by 1024MAK » Sun Jul 28, 2019 12:16 pm

So the power supply that the book talks about is most likely a mains to 12V AC transformer, a bridge rectifier and an electrolytic smoothing capacitor. This is called an unregulated DC power supply. Hence the high ‘loaded’ DC voltage, and the even higher ‘unloaded’ DC voltage.

If the ULA in the Lambda needs a 9V supply (see the link in my earlier post), then that explains why such a high voltage unregulated power supply is needed.

Mark

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