Footswitch LED issue

Silent Sound

Member
Messages
5,418
So I built and amp with a footswitch to change between channels. The footswitch just grounds out the channel not in use. It's an A/B/Y type of thing so I can switch between either channel, or use both. Here's a schematic:


http://www.jimmyharrisdesigns.com/FootSwitchSchematic.pdf

It's wired up with two LED's, a yellow LED and a tri color LED, both 5mm. The idea is, that the yellow indicates when both channels are being used, and the tri color LED is always on, either blue or red, depending on which channel is selected. It's always on, so you know if you'll be on the red or the blue channel when you turn off the Both switch and yellow LED.

Now for the problem. When I turn on the yellow LED, the blue LED goes off. The yellow LED works fine with the red LED. I've tried wiring them in series and in parallel, and both had the same problems. Even removing the current limiting resistor didn't do anything. I've tried wiring two batteries in parallel and series thinking it might need more power, and nothing. The forward voltage for the blue LED is listed at around 4v and the yellow at around 3v, which gives me 7v, well below the 9v batter I have to power them with. I've also replaced the LED's several times, and even went with different brands (more because I fried some LED's trying to figure this thing out). They're just standard 5mm LED's, so I wouldn't think they'd have a problem sharing a 9v, as I've made things before using 20 or so LED's and powered them off a single 9v. How many milliamps can a 9v put out? I don't think I've drawing too much current, and seeing as how I've ran two 9 volts in parallel, I thought that would have taken care of the current issue. I've even removed all the switches and just plugged the LED's straight into the battery (through a 100 ohm resistor because it fried an LED the first time I did this) and still can't get both to light up at once, so I know it's not the switches.

Anyone got any idea? Ever ran into this before? I know it's got to be something stupid, but it's got me stumped.
 

rumbletone

Silver Supporting Member
Messages
7,136
So I built and amp with a footswitch to change between channels. The footswitch just grounds out the channel not in use. It's an A/B/Y type of thing so I can switch between either channel, or use both. Here's a schematic:


http://www.jimmyharrisdesigns.com/FootSwitchSchematic.pdf

It's wired up with two LED's, a yellow LED and a tri color LED, both 5mm. The idea is, that the yellow indicates when both channels are being used, and the tri color LED is always on, either blue or red, depending on which channel is selected. It's always on, so you know if you'll be on the red or the blue channel when you turn off the Both switch and yellow LED.

Now for the problem. When I turn on the yellow LED, the blue LED goes off. The yellow LED works fine with the red LED. I've tried wiring them in series and in parallel, and both had the same problems. Even removing the current limiting resistor didn't do anything. I've tried wiring two batteries in parallel and series thinking it might need more power, and nothing. The forward voltage for the blue LED is listed at around 4v and the yellow at around 3v, which gives me 7v, well below the 9v batter I have to power them with. I've also replaced the LED's several times, and even went with different brands (more because I fried some LED's trying to figure this thing out). They're just standard 5mm LED's, so I wouldn't think they'd have a problem sharing a 9v, as I've made things before using 20 or so LED's and powered them off a single 9v. How many milliamps can a 9v put out? I don't think I've drawing too much current, and seeing as how I've ran two 9 volts in parallel, I thought that would have taken care of the current issue. I've even removed all the switches and just plugged the LED's straight into the battery (through a 100 ohm resistor because it fried an LED the first time I did this) and still can't get both to light up at once, so I know it's not the switches.

Anyone got any idea? Ever ran into this before? I know it's got to be something stupid, but it's got me stumped.
Hmm.... have you tried splitting the power before the current limiting resistor, and using a separate resistor for each of the LEDs (i.e., one for the yellow, and one for the bi-color), and try some different values for the CLRs - it may be that the different draws from the different color LEDs means that one is sucking all the current and the other is not getting enough to light up.
 

Silent Sound

Member
Messages
5,418
Hmm.... have you tried splitting the power before the current limiting resistor, and using a separate resistor for each of the LEDs (i.e., one for the yellow, and one for the bi-color), and try some different values for the CLRs - it may be that the different draws from the different color LEDs means that one is sucking all the current and the other is not getting enough to light up.
No, I haven't tried that. That sounds like a solid theory and is definitely worth a shot! Thanks!
 






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