More Amperage?

[dafortier]

I have a Furman SPB-8C pedalboard / power supply that has 8 dc outputs at 100ma max each.  Which is fine for most pedals.  However, I do have a few pedals that require more than 100ma.  Some at 9v, and some at 18v.  I have the schematic from the mfg and it looks pretty simple.  Each dc output has AC input from the transformer to a diode rectifier rated at 1amp, some capacitors and a transistor.  LM78L09ACZ.  The specs on the transistor say it's rated at 100ma.  I'm assuming that's where the 100ma limit comes from.  Would it be possible to replace that transistor with one that that has a higher amperage rating.  Like NJM78M09FA-ND.  (9v, 500ma).  See attached schematic for reference.

[reddesert]

The 78L09 is not a transistor, but a voltage regulator. (Same shape case as a transistor.) There are voltage regulators rated for higher current, like various kinds of 7809. These usually are in a larger TO-220 style case that has a metal fin that can be attached to a heat sink.

You might get away with direct swapping the regulator if your pedal doesn't draw much over 100 mA. Beyond that, you probably have to think about heat sinking the regulator - attaching the case to some large metal thing that isn't ground; and possibly about the rating of your transformer.  The data sheet for the voltage regulator should give some information about when a heatsink is required. Typically these regulators need to drop at least 3 volts, meaning your transformer + rectifier is supplying at least 12V. So if it was 12V and you were drawing 500 mA at 9V from the regulator, then (500 mA * 3 V) = 1.5 watts is being dissipated by the regulator. Doesn't sound like much, but inside a closed box, that could get the regulator quite hot.

[HamSandwich]

Before you start pulling more amps, you need to figure out if the transformer can supply them. What are the specs on the transformer? Could be a reason the decided to go 100mA and not 1A

[dafortier]

Someone else mentioned a bigger transformer as well. And a heat sync. I don't have the specs on the transformer but I'll see if I can dig it up.   Thanks! Glad I asked before I started swapping parts!