led indicator in a rangemaster clone running off -9v and ground, can it be done?

[njkmonty]

led indicator in a rangemaster clone running off -9v and ground, can it be done?

i have made an external power thingy in a 1590b enclosure with a LT1054
it does the usual , provide  9v +   , 18v + , and 9v-
just wondering if a led would work using -9v ?
or do i need to build the charge pump circuit/voltage inverter, into the rangemaster, and use the 9v+ for running the led?

ie my rangemaster works with the -9v, but no way visually to tell when on or off?

[slacker]

You do it the same as for running on +9 volts, you just have to reverse the connections to the LED.

So -9 volts >>> resistor >>> LED cathode LED anode >>> To stomp switch

[Kesh]

voltage is always relative to some other voltage

so between +9V and 0 is the same as between 0 and -9V

connection should go

0 => +LED terminal, -LED terminal => -9V

WITH A RESISTOR IN SOMEWHERE, and whatever switching you use, as normal.

[njkmonty]

thanks will give a go !

[R.G.]

There are -9V versions of the Millenium Bypass.