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+5V, +9V and +12V regulators from the same AC/DC adapter?


alchemist

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Hello,

 

Can I plug in parallel three 78xx regulators to get +5, +9 and +12V from the same 15V DC adaptor ?

Is it better to do that in parallel or serial (+12, then +9, then +5)? (its for a full MIDIbox SID set-up, with 4 cores, 4 6581 and 4 8580, hence the 3 voltages).

 

For now, I plug a 9V DC for +5V and 15V DC for +12, but I would like to minimize the AC adaptors.

 

I don't see a problem, but I could say an heresy, and would be sure I wouldn't overload the 78xx with too high voltage or drained current.

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alchemist,

You can plug them in series, that way the step-down and therefore temperature on the individual stages will be much lower but beware that the "earlier" regulator in the chain needs to be sized for the following stages as well! This might result in a 3A package (TO3) with a heatsink for the 12V stage, maybe even the 9V. Also, the transformer needs to be properly sized. Of course, this depends on the actual power you need.

Htg,

freddy

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Hello,

 

Thank you for the reply !

 

The power needed would be for

- 4 x MBHP_CORE

- 8 x MBHP_SID

- 2 x MBHP_DOUT

- 3 x MBHP_DIN

- 4 x SID 6581 (+12V)

- 4 x SID 8580 (+9V)

- 1 x LCD display (20x2)

- and about 80 LEDs for the Control Surface

 

At term, I will use a C64 PSU, but this will come later, and I would like to use an other PSU before I get it.

 

I will check the power needed by element, then compute the power consumed by each 78xx regulator.

Edited by alchemist
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