78LM09 Supply Current

Frequently asked questions regarding powering your pedal.

78LM09 Supply Current

Postby newly » 27 Jun 2010, 19:12

Just learn from data sheet that 78LM09 only capable to deliver 100mA.
If i put 2 pcs of 78LM09 in parallel, would it able to supply 200mA?
My transformer is capable to supply 250mA.
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Re: 78LM09 Supply Current

Postby mictester » 28 Jun 2010, 00:08

newly wrote:Just learn from data sheet that 78LM09 only capable to deliver 100mA.
If i put 2 pcs of 78LM09 in parallel, would it able to supply 200mA?
My transformer is capable to supply 250mA.


No. Don't try it - you'll fry one or possibly both of them. They're never exactly 9V, so one will "fight" with the other.

If you need more current, go for the 7809, which is fine to 1 Amp. At 250 mA, this regulator will run cold, so won't need a heatsink (unless you're trying to drop down from 30 Volts!). One useful thing to remember - you must connect two 100nF (0.1µF) capacitors right at the IC pins - from input and output to the centre pin (ground). This gets rid of any noise on the supply rail generated by the regulator IC, and prevents RF breakthrough.
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