Continue to Site

# Hot resistors. help !

Status
Not open for further replies.

#### Sunny55

##### Full Member level 3
I hooked up a voltmeter circuit to a car battery and the resistors connected to the LEDs got hot. My solution is i plan to apply a line of solder along the output points. Am i doing the right thing? Can more solder = higher heat dissipation?

Can you show us the circuit and the resistor value/rating

If the resistor is not of an appropriate power rating and gets overheated they why not use a higher power resistor , there are several power ratings (1/4, 1/2, 1, 2, 5, 10W..).
You cal also reduce the led current using a higher value resistor.
Another option is to achieve the same value using two resistors in series or in parallel to share the heat dissipation

The resistors are 1kohm and i m using 1/16 w for power rating i guess. I do not have extra resistors. Can i just apply thick solder along the resistors path to reduce heating?

The standard resistors are 1/4W , are you using smd resistors?

The power on the resistor is P=V²/R so can you measure the voltage across the resistor so we know what is the power consumed there (and also get an idea of the led current)?

Well given you're connecting this to a car battery nominally 12V then you've got at most 12 mA flowing through the resistor.

Given you are using a 1/16W resistor....

the actual requirement would be instead P=I^2R or (0.012)^2 * 1000 = 0.144 W which is higher than the 0.0625 W of a 1/16W resistor.

Running that much current through the resistor will damage it. Haven't experimented with the failure mechanism for resistors so can't say if it will fail as an open or a short (I suspect an open).

Status
Not open for further replies.