# Tag Info

### Is there ever any reason to prefer 5% tolerance resistors over 1%?

Although answered in several ways here correct, it boils down to the the type of circuit. If one is building an audio amplifier, some looseness is good, and the ceramics are more forgivable under load....

### Insulation resistance or isolation resistance?

Insulation resistance is used when measuring resistance between two materials, one being a conductor and the other an insulator, these two materials must have physical contact! Isolation resistance is ...

### How do I create a circuit to reliably calculate a range of unknown resistances?

You can do this, I've been able to calculate resistances down to the tens of milliohms. This circuit is also useful for calibration and delivering a known amount of power. The problem you have is you ...
• 85k
Accepted

### Why do I have to increase the current by 2V when I am using a transistor?

It is dim because the collector-emitter saturation voltage for your transistor is ~2V. Use a logic level MOSFET and a current limiting resistor. You won't be able to get full brightness with a 3V ...
• 20.4k

### Why do I measure different resistances in the same wire at different current levels?

My first comment would be regarding your poor measurement configuration that will surely not give very accurate results. The voltage taps (I guess these are the crocodile clamps) position is not well ...
1 vote

### How do I create a circuit to reliably calculate a range of unknown resistances?

There is a lot of circuitry in your solution with plenty of areas where errors can be introduced. A Wheatstone bridge is probably more suitable (and simpler) for what you are trying to do. It relies ...
• 616

### Testing to find polarity of PCB power connector

The M in front of Ω means million. So you read very high resistance values here and they will not tell you anything useful. A negative resistance value should tell you, that this measurement method ...
• 7,347
1 vote
Accepted

### Testing to find polarity of PCB power connector

On the big electrolytic capacitors, there should be some indication of polarity (often only - is marked). Put your multi-meter in continuity mode, and check if the pads from the capacitor show ...
• 7,697

Top 50 recent answers are included