LED is bright when I turn it on and quickly goes very dim?

[JimiB]

This is on a treble booster (rangemaster clone I built) What could cause this?

[R.G.]

A whole lot of things could cause that. It's impossible to tell unless you can tell us what you have hooked up, what schematic you were trying to wire up, what components, etc.

[zenpeace69]

This is on a treble booster (rangemaster clone I built) What could cause this?

How bizarre!  I just built a rangemaster a week or so ago and when I hooked up the switch and LED the other day I got the same thing.  Kind of like a quick power surge to the LED and then it stays on, but kind of dim.

[zenpeace69]

Here is a link to the schem I used:

http://www.boardsprep.com/mp3/DallasRM2.jpg

What could be going wrong?

[zenpeace69]

The weird thing is, it's just the LED wired between the switch and the battery snap.  What could be going wrong?  I am using a 2k2 resistor.  Should I try something else?  Lower/higher value?

[cd]

I bet you're using a positive ground effect, but have the LED's cathode to ground, right?

[aron]

How quick does it dim? Try a 1K resistor and just connect it manually between the LED+resistor and battery to test the brightness.

[Peter Snowberg]

Have you tried a new battery?

[R.G.]

Once again, what exactly are you trying to wire up?

That schematic doesn't show any LED nor any switch. If you are trying to wire up the original Rangemaster wiring where the power is switched on when the effect is engaged and you have wired the LED in series between the battery snap, the switch and the effect, then the LED is coming on initially because when the power comes on, the battery is trying to charge that 25uF cap. The current flows and the LED is bright until that cap charges, then it dims down to whatever current the circuit uses.

... if that's what you wired up. As I say, I can't tell what you tried to wire up.

[zenpeace69]

Once again, what exactly are you trying to wire up?

That schematic doesn't show any LED nor any switch. If you are trying to wire up the original Rangemaster wiring where the power is switched on when the effect is engaged and you have wired the LED in series between the battery snap, the switch and the effect, then the LED is coming on initially because when the power comes on, the battery is trying to charge that 25uF cap. The current flows and the LED is bright until that cap charges, then it dims down to whatever current the circuit uses.

... if that's what you wired up. As I say, I can't tell what you tried to wire up.

Well, I wired it up like you would with a 3PDT switch.  I did the in and out from the circuit and I wired up the LED from the switch to the battery snap.

[Transmogrifox]

Are you switching the power supply on with the LED in series with the circuit?
For example:  battery snap(+) at ground.  battery snap(-) --->switch--->rangemaster circuit---->return to ground
I would have to go with RG in that case.  It does really sound like you are switching it on, the battery is charging up that 25uF cap (bright LED for a short period of time) then going to steady state.

If this is the problem, then put a 4.7k resistor in parallel with that 25 uF cap.  If its too bright, make it bigger (like 10k), if too dim, maybe 3.3k, 2.2k, God help us if you need it brighter than that!

Another thing to do is to leave the circuit "in idle" whenever the jack is connected and just connect an LED/Resistor assembly in parallel to the battery with the switch set to complete the circuit while on, break it with bypass position.  You need a stereo jack to do this.

[Paul Perry (Frostwave)]

Suppose you WANTED to make the led do that, y9ou coulde do it by putting the led in series between the battery and the rest of the circuit. A rush & bright when the electro charges, then dimmer, but strill glows.

[Paul Perry (Frostwave)]

Suppose you WANTED to make the led do that, you coulde do it by putting the led in series between the battery and the rest of the circuit. A rush & bright when the electro charges, then dimmer, but still glows.