Resistor Modding

Flashlight Modding and DIY Parts
1

I am sure most of you are familiar with the smallsun ZY-T08. I my self purchased a pair and followed suit doing the .22ohm resistor mod stated in one of the threads. Now I have done it and all is well, brighter than before and works well but why?

Can someone explain the reasoning behind adding a resistor to the driver circuit?
How is the math calculated for this and what is the resistor affecting?

Thanks

2

Sorry I cant help but great question! Im interested in the answer as well.

3

Is that the sense resistor?

4

I’m not familiar with this mod (and not even with electronic circuits) but most probably you are adding a resistor in paralel to an already existing one on the driver and therefor the new Resistance can be calculated by

1. multiplying the two resistance values
2. adding the two resistance values
3. calculating the final resistance by dividing the multiplied value by the added value

In total the resistance is lowered under the lowest resistance already present in the circuit
and if this is used to “tell a transistor” how much amperes he should let pass through it will increase
the power (amperes) to the LED.

Hope the electronic gurus here will correct me if i am wrong.

Mo

5

Well, exactly as JML said, it is the sense resistor your regulator is looking at. If you add a resistor parallel to the existing you end up with a lower sense resistor. Regulator assigns a fixed voltage over this sense resistor and the current through it becomes dependent to the resistor value as V = I x R. The output current must be something multiplied by this sense current. Lower the resistor higher the sense current and higher the output.

6

Okay. I did read some about a sense resistor, while I dont know exactly what it is I know what it is supposed to do.
How does one know which resistor would be the sense resistor? I have seen them labled with a preceding “f” before a number.

Original mod here

7

That should be an “R” before the digits, which means 0.xxx Ohms. Sense resistors usually have small values so you’ll find it easily. The smallest value resistor will most probably be the sense resistor.