Wiring a Switch (on-on) to Select Between LED and Diode

[charles]

Hi guys,

I am trying to do DS-1 mod in Fuzzcentral.
How shall I wire a selector switch to switch between a LED and a diode?

Instead of completely replacing one of the clipping diodes to LED, I wanna get both sounds by adding a switch.

Thanks!

[RickL]

Wire it so that the LED is always in the circuit. Wire the diode in parallel with the LED through a spst switch. When the switch is open only the LED is active. When the switch is closed the lower voltage drop of the diode will kick in before the LED, as if only the diode was in the circuit.

[charles]

Thanks Rick.

How would it be different with dpdt switch?  I got on on lying around...
(obviously...I am a beginner here... :-) )

[RickL]

Although it's a bit of a waste you can wire the dpdt exactly the same way. Use one of the middle lugs and one of the outside lugs, it will operate as a spst switch.

123
456

dpdt switch lugs viewed from the back.

Use 1/2 or 2/3 or 4/5 or 5/6.

Note, if you have a spdt or dpdt switch that is centre off (the toggle has 3 positions instead of 2) you can choose between 3 sets of diodes. Just connect the third set of diodes (or third diode if you're only switching one diode at a time) to the open lug on the switch. The other end of the diode(s) goes to the same place on the board as the free end of the first switched diode(s). This would let you choose between, for instance, LED, silicon and germanium diodes.

In the above diagram silicon would go to 1, wire to the circuit (one end of LED) to 2 and germanium to 3. Free ends of both silicon and germanium would go to the other end of the LED in the circuit. Just make sure you keep the polarities of the diodes the same if you're only switching one diode at a time.

[charles]

Thanks Rick!

[modmod]

sorry i dont quite understand how to do that with on-off-on spdt toggle , say if i wanna switch between led,1n4001,1n4148. how should i wire them all into 1 spdt ? could anyone kindly draw a simple diagram of that ? thx

[modmod]

Wire it so that the LED is always in the circuit. Wire the diode in parallel with the LED through a spst switch. When the switch is open only the LED is active. When the switch is closed the lower voltage drop of the diode will kick in before the LED, as if only the diode was in the circuit.

am i correct ?

[modmod]

sorry,the correct link here
http://community.webshots.com/photo/286586371/286589047RcQPdN

[Khas Evets]

You can do it that way to control one side, or wire back to back diode pairs using the same switch.

[modmod]

Wire it so that the LED is always in the circuit. Wire the diode in parallel with the LED through a spst switch. When the switch is open only the LED is active. When the switch is closed the lower voltage drop of the diode will kick in before the LED, as if only the diode was in the circuit.

so led and 2 other diodes will only active ONE at a time with just a single spdt ?

[RickL]

Short answer, yes. In the middle (off) position only the LED is active. In each of the other two positions the other diode will conduct before the LED, so the circuit acts as if the LED isn't there.

[Sebacore]

How would that diagram be different is it was a spdt on on?  If someone could just do a diagram of that like the one above that be great.  Thanks

edit:  Nevermind i just looked at it a little harder and figured it out