Boss CE-5 Rate LED

[aviherman5]

Hey all!

I wanted to trick out my analog Boss CE-5 by adding a relay bypass, switch to switch between 5pf and 22pf for C22, add a vibrato toggle switch, and add a flashing rate led.

I know how to implement the relay switching and the switches, but I have no idea how to implement the flashing rate led. Although I see it's been done here:

Here is the schematic:


Any ideas on how to do this (noise and tick free)?

Thanks for all the help in advance!

[aviherman5]

After some further thought, is the solution to attach the anode of the LED through a resistor to this spot right here?



I saw a CE-2 layout with an LED, and that is what is demonstrated here (through a 22k resistor)


Thoughts?

[antonis]

As long as LED current doesn't load Q5 Emitter significantly (which is the case here), it should be OK...

[anotherjim]

It will depend on the depth setting won't it if you copy that?

I'd pick IC4b pin 7. You'll need to pick the resistor to suit since it will light according to the triangle wave from the LFO so the average light intensity will be reduced - it will throb rather than flash and only be fully lit briefly at the positive peak of the triangle sweep.
If you wanted the LED to flash you'd use IC4a pin 1 as that's a square wave although this risks getting ticking noise in the audio as the LED current switches on & off, but it would reach full brightness while it's on.

[Ripthorn]

Would it be possible and less tick prone if the square wave was tied to the base of a bjt that had collector to LED cathode and emitter to ground? Then the LED current isn't being drawn through the LFO.

[aviherman5]

Let the record show that pin 7 of IC4b works perfectly!

Except for the fact that it really only works with the depth all the way up 

Any fixes for that?

[Electron Tornado]

Here's how I did the pulse LED. Component numbers are with reference to the Boss CE-5 factory schematic, according to my notes.

Cathode of LED to pin 1 of IC4A. Can use C34 or R53 where they connect to pin1. (Come to think of it, you can also use lug 3 of the rate pot - the lug connecting to off-board wire connection 9 in schematic.)  Anode of LED goes to 4.7k resistor, which then goes to ground. The LED I used was a 5mm red LED.




In other mods: It's also worth trying different values of capacitance in the C21 to see what you like. I have a setting, (can't recall cap value) that gives a subtle flange.

[aviherman5]

So I just figured out your method on my own and it's totally functional

I do like it when it does the slow pulse triangle wave thing and not the square on/off wave though, so any tips on getting that to work with the depth knob?

[Electron Tornado]

Glad you got it working!

I've been happy enough with how mine works, though. I do pulse LED mods just for the user to be able to see the tempo of the rate, so they can set it without having to engage the pedal.

Try the other mod I mentioned while you've got it on the bench.

[aviherman5]

Yes! It's the C22 mod which nobody identified sonically, but it's supposed to be pretty good. I plan to add a switch to switch between the 5pf cap and a 22pf cap as well as add a switch to toggle vibrato mod by shorting the B output

[anotherjim]

Let the record show that pin 7 of IC4b works perfectly!

Except for the fact that it really only works with the depth all the way up 

Any fixes for that?

It shouldn't have anything to do with the depth setting. The opamp pin 7 should be capable of driving the LED without affecting anything.
What value resistor have you used to feed the LED anode? What type LED? Does the LED cathode go straight to 0v?
Unless it's a high efficiency/ultra bright LED, I would expect the resistor needs to be as low as 4k7.

[aviherman5]

I shouldn't have anything to do with the depth setting. The opamp pin 7 should be capable of driving the LED without affecting anything.
What value resistor have you used to feed the LED anode? What type LED? Does the LED cathode go straight to 0v?
Unless it's a high efficiency/ultra bright LED, I would expect the resistor needs to be as low as 4k7.

I'm using a 5.1k resistor. It goes almost staticlly on at zero% depth

[anotherjim]

It's likely the LED may never go black as the output from pin7 won't swing from 0v to 9v but maybe 1.5v to 7.5v. A standard red LED needs about 1.5v so it will only vary in intensity rather than flash.
I think something must be wrong somewhere or the extra load current for the LED is pulling the 9v supply voltage down. Is your 9v supply stable? Weak battery?

[aviherman5]

It's likely the LED may never go black as the output from pin7 won't swing from 0v to 9v but maybe 1.5v to 7.5v. A standard red LED needs about 1.5v so it will only vary in intensity rather than flash.
I think something must be wrong somewhere or the extra load current for the LED is pulling the 9v supply voltage down. Is your 9v supply stable? Weak battery?

Battery measures 8.9v so no. It definetly doesn't go dark!

[anotherjim]

Try it in "reverse". Resistor from +9v (IC pin to LED anode. LED cathode to IC pin7.

[aviherman5]

Will try tonight!

[anotherjim]

The  is, of course, pin 8.