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MITS Altair 8800 Power Supply


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  MITS Altair 8800 Power Supply by Bill Degnan - 08/03/2012 14:54
Pictured is a MITS accessory box. No I do not have original MITS power supplies for sale or otherwise.

ALTAIR 8800 original power supply specifications (at the end):

(From Dan Roganti [CORRECTED])

T1 transformer
Output = 8VAC, 8A
This is used to power the TTL logic on the cards in the backplane(+5V). It was very underpowered
when many of the slots were populated with cards.

T2 transformer (dual output) :
This is just a strange part just so they can have a separate 8VAC power supply. This is a "nice-to-have" part but
it's entirely unnecessary. Because the Front Panel can't operate without power on the CPU and the CPU can't
operate without power on the Front Panel. They just had some unwarranted concern where the Front Panel needed
a separate 8VAC transformer.

Output 1 = 8VAC, 1.2A
Output 2 = 24VAC CT, 400mA

Output 1 is used to power the TTL Logic on the Front Panel (+5V)
Output 2 is used for +12 V power to components such as the RS232 MC1488 receivers and the 8080 cpu

T3 transformer

Output = 11VAC, 300mA - this is used for the -12 V power

This provided the negative supply voltages for components such as the RS232 MC1488 receivers(-12V) and the 8080 cpu (-5V)

Parts Suppliers


T1 : Stancor, part# P-6138
This can be used to power the Backplane and the Front Panel - providing you only limited the amount of cards in the system.

T2 & T3 Jameco part# 221400 12VCT, 2A
With two of these you can get the +12VAC and -12VAC for the backplane

T2/T3 Stancor part# P-8364 dual secondary xmfr, +12VAC, 1A & -12VAC, 1A
With just one of these, you get both +12VAC and -12VAC inside one xmfr - so it saves space

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