simple millenium bypass question (vero)

[blanik]

the only vero i could find for the mill bypass here is this one:



is the 2k2 the LEDs current limiting resistor (it's on the ground side of the LED?!) and if so can it be raised to 12k or does this circuit need a current limiting resistor on the + side of the LED in addition?

[JKowalski]

No, that's correct. The 2.2K resistor can be on either side of the LED, it does not matter. It is the current limiter.

To turn on the LED, the voltage across it has to be about 1V. If you put it before the resistor, first the LED drops the voltage 1V, then the resistor drops it the rest, 8V. If you have it after the resistor, first the resistor drops the voltage 8v, then the LED drops it the final 1V. Regardless, it still has 1 volt across it each way, so it still turns on.

The limiting of the current can be on either side, because, either way, it will limit the current throughout the whole circuit it in the same way.

[blanik]

No, that's correct. The 2.2K resistor can be on either side of the LED, it does not matter. It is the current limiter.

To turn on the LED, the voltage across it has to be about 1V. If you put it before the resistor, first the LED drops the voltage 1V, then the resistor drops it the rest, 8V. If you have it after the resistor, first the resistor drops the voltage 8v, then the LED drops it the final 1V. Regardless, it still has 1 volt across it each way, so it still turns on.

The limiting of the current can be on either side, because, either way, it will limit the current throughout the whole circuit it in the same way.

ok fair enough, but if i raise the value to 10k-12k (my usual values for hi-brite LEDs) will the circuit work the same?

(on a parallel note, if i put the resistor between 9V+ and LED +, do i have to put a jumper in place of the 2k2?)

[JKowalski]

Yes on the jumper - but there's really no point. It will just make the layout more complicated.

Basically - the circuit, in the on state, would work almost EXACTLY the same as just having the LED and its current resistor. So if you have a typical proven resistor value for your LED, then just use that.

[dcd666]

the only vero i could find for the mill bypass here is this one:



is the 2k2 the LEDs current limiting resistor (it's on the ground side of the LED?!) and if so can it be raised to 12k or does this circuit need a current limiting resistor on the + side of the LED in addition?

does it work with 12V ?

[JKowalski]

Yes, but you will have to increase the current limiting resistor slightly - ohms law.

V=IR, or V/R=I. If you keep the same R but increase the V, the current, I, will increase. Therefore you must increase R to compensate.

[JKowalski]

As for the millenium bypass, I have found that it is actually possible to "make your own" component. Find a really tiny box or something, wire the parts together point to point in as small a room as possible, and then set it in the box and pot it (I just put a big blob of epoxy in mine). This way you can make a very tiny box with three leads and the led coming out of it, and from there it's a simple matter to wire that to your 9v+, ground, and control. Sort of like this:



Just be careful the leads inside the case don't touch! Once you pot it you cant go back!