Neovibe status LEDs

[axg20202]

Hi all,

this is the third of my recent threads about this build. Today I've been messing around with using status LEDs in the switching for true bypass and for the vibe/chorus selections. I thought I'd share my experiences because I had trouble finding these details myself when I did a search of previous posts. A bit of what follows was pieced to together from other posts (not all of which were correct) but most was from trial and error.

First of all, I put together the Vibe/Chorus switch with status LED. I decided it would be cool to use a two-colour LED for this. To do this, you'll need a DPDT switch and the bi-colour LED (the kind with 3 leads). The one I used had a commone cathode and an anode for each colour (red and green in a single 5mm LED), but one with a common cathode and an anode for each colour will work just as well - it will just need to be hooked up to the switch differently. Whichever type you use, all you do is use the three lugs on one side of the switch to work the actual chorus/vibe selection as per RGs layout (from GGG) and the other 3 lugs of the switch to work the LED. For a common-cathode-type bi-colour LED, the middle lug of the 3 LED-controlling lugs of the switch receives the power from the circuit board (via a 2.7k resistor, or thereabouts) and the other two lugs of the switch feed this to each of the two anodes (one for green, one for red). The cathode of the LED is obviously just connected to a ground somewhere on the board - I used the ground pad that forms part of the 'cancel' switch (pad I). The 15v power for the LED can come from the spare O(utput) pad at the point on the boad where your 7815 mounts - there is a spare pad to accomodate one of the two different package types for this IC (note: I'm NOT referring to pad O on the board (below J on the layout), which is just a ground). Just connect this pad to a 2.7k resistor and then onto the middle lug of the switch. So, now whenever you switch between vibe and chorus, the LED will change from one colour to the other.

Secondly, I turned my attention to the true bypass 3PDT switch and LED. I wanted to make this not only come on and off as per the usual effect/bypass LED - I wanted it to pulsate at the speed of the vibe LFO as well. Two indicators in one. Again, this is easy to do. You'll need a 100K miniature trim pot for this (and an LED...duh!). All you do is wire up the cathode side of the LED to your 3PDT as per your garden variety effect/bypass LED. The only difference here is the point you take your power from to connect to the anode of the LED and a trim pot to control the juice provided. Obviously, if you take your power from an oscillating part of the circuit, the LED will throb in time. So, here's what you do. Tack solder a thin piece of hookup wire to the Base (B) of Q12 and connect the other end to the left-hand lug of a 100k trimpot. Connect the wiper of the trimpot to the anode of your LED. Then connect the cathode of the LED to the appropriate lug of your 3PDT. This works fine but I think a high brightness LED is required to get it lit well - I have a standard one in at the moment and its not bright enough compared to the vibe/chorus LED. The 100k pot sets the brightness, but it also has an effect on the tone of the circuit - as someone else mentioned in another post, it acts like another bias control. If the resistance of the trimpot is set too low, the LED draws too much power and can make the circuit sound choppy. The trick is to adjust the 100k pot for optimum LED brightness while retaining good vibe that doesn't sound choppy like a square wave tremolo.

Anyway, I hope this helps someone.

Andy.

[andrew_k]

Anyway, I hope this helps someone.

It sure did, thanks 

[mdame]

Could you do this with a DPDT and millenium bypass?  Just take the +9v for the led circuit from the oscillator?