Electronics guys - Design me a simple backlight circuit.

[Gearjoneser]

Here's the deal. I'm building a new pedalboard around a cool piece of metal I found that's full of ventilation holes. It was a shelf on a computer desk I found by the trash! :fingersx: When it's done, I'll post pics in a day or two.

Anyhow, I'm thinking of placing 4 mini lightbulbs underneath it in a loop around the lower perimeter, so the light is visible through all the vent holes.
I'm wondering if it should be powered by the power supply, or if I should put it on it's own battery circuit, with a mini switch?

Explain a circuit, or show me a schematic, if possible. My plan is to glue 4 sockets under the metal panel, all connected by a hot and ground wire, and probably a resistor, and mini switch. I'll isolate it from the board surface, so the metal panel doesn't become a ground. Very simple, but it can't bleed a 9 volt battery too quickly.

 

[greco]

Re: Electronics guys - Design me a simple backlight circuit.

What about using LEDs ? I'd use a separate circuit and a mini toggle. Easy to build and lasts a long time. Various colours and levels of brightness are available.

 

[Rich_S]

Re: Electronics guys - Design me a simple backlight circuit.

I, too would use LED's, but on their own power supply instead of a battery. You could hack the connector off practiacally any wallwart. You do save wallwarts when their associated equipment dies, don't you? (If not PM me - I have a whole drawer full of them.)

You'll need to wire your LEDs in series with a dropping resistor, but its value will depend on the type & quantity of LEDs, and the voltage of you wall wart. Get them picked out first, then we'll figure out the resistor.

 

[ratherdashing]

Re: Electronics guys - Design me a simple backlight circuit.

Go buy a strand of those LED Christmas lights - that's your best bet.

 

[loudriver23]

Re: Electronics guys - Design me a simple backlight circuit.

Go buy a strand of those LED Christmas lights - that's your best bet.

Now we're talkin!!!!

 

[fingerace]

Re: Electronics guys - Design me a simple backlight circuit.

I, too would use LED's, but on their own power supply instead of a battery. You could hack the connector off practiacally any wallwart. You do save wallwarts when their associated equipment dies, don't you? (If not PM me - I have a whole drawer full of them.)

You'll need to wire your LEDs in series with a dropping resistor, but its value will depend on the type & quantity of LEDs, and the voltage of you wall wart. Get them picked out first, then we'll figure out the resistor.

Isn't it better to have them in parallel ? so that if one goes out, the others don't? (they may as well go out if they are parallel not that I think of it...) anyway...

Also I'd recomend getting a "strong" transformer for your power supply (eg 12volts) they are not that expensive. + a strong variable resistor... and using a multimeter work from there to match the voltage the LEDs need using the variable variable resistor as a potential divider. This way, you can vary the voltage to match exactly what you need.

I don't know if this was exactly what you wanted to do GJ.... anyway hope I helped...

 

[Artie]

Re: Electronics guys - Design me a simple backlight circuit.

Isn't it better to have them in parallel?

I think he was refering to the series resistor. Each LED needs to have a current limiting resistor in series with it so that it won't burn up. Like so:

You calculate the value of the resistor by taking the power supply voltage, subtract the forward voltage of the LED and divide by the forward current. So, if you used 12 volts and the FV of the LED was 1.2 and the If was 20 milliamps, you'ld have:

(12 - 1.2) / .020 = 540 ohms

 

[fingerace]

Re: Electronics guys - Design me a simple backlight circuit.

Each LED needs to have a current limiting resistor in series with it so that it won't burn up.

Oh, I didn't know that... Is that always the case?
I kind of expected you to show up and wait to see if I made a mistake!

 

[XSSIVE]

Re: Electronics guys - Design me a simple backlight circuit.

regular light bulbs put off heat, that's the last thing i'd want under a pedal board. go with cold cathode lights like they use in computers. they look like neon light tubes if you're not familiar with them and come in all colors.

-Mike

 

[Gearjoneser]

Re: Electronics guys - Design me a simple backlight circuit.

Thanks guys. I still haven't decided if I want the whole light thing, but I may cheat and do it the easy way.....find a couple little cold cathode light strips with their own battery compartment, and glue them underneath. I'll only turn them on if it's a dark room and I want the display.

The pedalboard will look pretty cool. The main board is forest green metal w/vent holes. The sides will be amber stained wood, kinda like Moog pedals or old mixing consoles. The board will have a slight angle too. This will be my 'smaller' board, and all the pedals will be white, gold, and green.
(Fulltone Clyde Deluxe, Klon, white FDII, green Fulltone Choralflange, tuner, powersupply.