Dr. Phybes rate LED

[Anonymous]

So I have built several Dr. Phybes circuits and used the rate LED mod that was detailed in the old forum. However that rate LED gives only an on/off LED at the speed of the phaser. What I would like to know is if there is any way to add a rate LED that pulses rather than just on/off? Looking for something like the rate LED on the EA tremolo, Apollo tremolo, or some other phaser circuits I have seen. Thanks for any input!

[Anonymous]

I believe this is what you seek:

Rate LED Mod as posted by Tim Shelton

Patrick Garland (words) and Schectadon (picture for Dr. Phybes

 

1. Solder a Limiting Resistor to the POSITIVE side of the LED (Round) – on Blue LEDs I use a 3k9 Resistor

2. Connect a wire to the Resistor, and solder the wire to 9v

3. Connect a wire to the NEGATIVE side of the LED (Flat)

4. Connect NEG LED wire to lug 3 of Speed Pot

 

[Anonymous]

Thanks, that’s the way I have been wiring it, which works fine and gives a blinking on/off led in time with the rate.  I was just wondering if there were a way to wire up a rate led that pulsed from off, growing steadily brighter to on, the steadily darker to off?

[Anonymous]

Sorry, I don’t know how to design that.

[Barry]

LEDs can be dimmed in two ways: analog and pulse-width modulation (PWM) dimming. Despite its attractive simplicity, analog dimming can be inappropriate for many applications because it loses dimming accuracy by about 25 percent+ at only 10:1 brightness levels. Pulsing is a more complicated animal.

 

[Anonymous]

Thanks guys.  I was hoping there would be just a different place on the Dr. Phybes circuit that I could attach the LED to get that dimming pulse.  I will have to consider if I want to just go with the blinking rate LED or tackle the more involved animal that is the dimming pulse LED as outlined above.  Appreciate the help!

[Anonymous]

try a large lytic cap in parallel w the resistor. Tc = 1/R*C(something like that 67%) = dlo on, slo off…..

 

[Author]

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