Delta labs chorus pedal schematic?

[yba-1 user]

does anyone have a schematic of the Delta Lab SC1?
It picked one up to tinker with.
I would like to put a brighter LED in it but it seems to have a tiny little board mount style and I am not sure if it has the resistor built in or if it is some where on the PCB.

[Mark Hammer]

That's the trouble with surface-mount boards; it's hard to see what connects to what.

I'm assuming that the LED is situated in the middle of the triangle, and directed mounted to the board with a little plastic cylinder holding it upright (or something like that)? This may be trickier than you think. Certainly feasible, but the nature of your questions suggests it is currently juuuusssst a bit beyond your chops. Come back to it in a year or so.

[yba-1 user]

That's the trouble with surface-mount boards; it's hard to see what connects to what.

I'm assuming that the LED is situated in the middle of the triangle, and directed mounted to the board with a little plastic cylinder holding it upright (or something like that)? This may be trickier than you think. Certainly feasible, but the nature of your questions suggests it is currently juuuusssst a bit beyond your chops. Come back to it in a year or so.

yeah it is a tiny little micro LED mounted on the board with a plastic cylinder on top of it.
The board is marked with LED pos and neg so I hooked up a different LED to the board and it does not light.
That is why I was wondering if that micro little LED had a resistor built in.
I did wire a resitor inseries with the negative lead but it still will not light.
Hmm any thoughts?

[yba-1 user]

yeah it is a tiny little micro LED mounted on the board with a plastic cylinder on top of it.
The board is marked with LED pos and neg so I hooked up a different LED to the board and it does not light.
That is why I was wondering if that micro little LED had a resistor built in.
I did wire a resitor inseries with the negative lead but it still will not light.
Hmm any thoughts?

Just hooked it up directly to the footswitch instead of the board.... works like a charm!
Juuuusssst within my chops ...LOL and didn't have to wait a year !

[Mark Hammer]

Heh, heh. Congrats!

Time flies when you're building chops, eh?

Just out of curiosity, would I be correct in assuming there is an 8-pin chip with "3207" written on it in there?

[yba-1 user]

I'll check next time I open it up..... I didn't pay attention before I put it back together

[doctor]

I'll check next time I open it up..... I didn't pay attention before I put it back together

In order to increase LED brightness you need to increase LED current. As a rule a designer sets this current about 5mA (and even lower) in order to save battery life. You can increase this current up to 15mA without fear. For this reason you need to find current limit resistor (it is connected serially with LED) and change it as needed.

There are two cases in accordance with LED color. If color is blue, voltage drop on the LED is about 3.5V, if color is not blue, voltage drop is about 1.7V.
If pedal is supplied from 9V battery, voltage drop on the current limit resistor is 9V-3.5V=5.5V for the first case, and 9V-1.7V=7.3V for the second one. Resistor values should be equal correspondently 5.5V/5mA=1.1K and 7.3V/5mA=1.5K. Clearly these values may be slightly different. In order to set the current equal to 15mA resistor value for the first case should be equal 5.5V/15mA=360 Ohm and for the second case 7.3V/15mA=470 Ohm correspondently.

Take into account that power of the new resistor should be also increased by 3 times.
This means that you need to use the next larger resistor’s footprint (for example 0805 instead of used 0603). To solder it on the existing smaller footprint is not a big problem.

If the taken action was not sufficient, you need also to replace LED with new one (with the same footprint) having higher light intensity (200-400mcd instead of common type used 20-50mcd).

Good luck,

[Mark Hammer]

With the widespread availability of inexpensive 3mm LEDs with ratings of over 10,000mcd (!!), it's easy to install other LEDs that draw less current to achieve the same brightness, extending battery life a bit.