A MOSFET will be a good choice.
The following gives a guide to directions - ask more questions.
Load max sounds like (pun notice retrospectively) LED strips at 12v, 10A
MOSFET needs to switch this load so 20V+ rating desired, usefully more than 10A - say 20A+.
Now the fun begins.
If the FET is hard on then dissipation is low. With and Rdson (= on resistance) of say 10 milliOhm the power loss at 10A due to channel resistance = I^2R = 10^2 x 0.01 = 1 Watt.
If you PWM switch the FET you add switching losses but losses are still "moderate"
If you linearly switch the FET so it acts like a resistor dissipation is much higher.
A 12V LED strip will decrease to close to 0% current by 8V (or higher) probably, so if full load is 10A you will probably be down to 5A at 10V (so driver loss = (12-10) * 5 = 10 Watts, and down to say 1A at 8V (loss = (12-8)*1 = 4 Watts.
So you can probably expect losses in linear mode to be under say 10W but allowing for 20W may be safe. Rdson becomes non-critical when used this way as resistive on losses swamp Rdson.
So, we have a MOSFET rated at ~~~= SOME OF 20V, >10A and 20W actual dissipation and Rdson = 10 milliOhm.
I say "some of" as you don't need Rdson low in linear mode but you don't need as hogh dissipation in PWM mode.
For 1 off amateur use specify leaded TO220 package for easier use and ease of heatsinking.
Searching DIGIKEY with
MOSFET 30V 20A TO220
then sorting by ascending price and looking for lowest $ in stock 1 quantity parts gives as below. I didn't specify Rdson but could have.
Infineon PSMN022-30PL - datasheet here in stock at 73 cents US in 1's. Pricing
30V, 30A, TO220, Rdson 34 milliOhm max at 5V gate drive, 41 W max dissipation,
See fig 1 for max dissipation based on heatsink temperature.
Thermal resistance is 3.6 C/W junction to case so you'd want to keep dissipation under 20W and ideally under 10W - SO probably OK.
So - how do you drive this.
You MAY be able to drive it straight from the amp with a potentiometer to adjust level. MOSFET in linear mode, probably.
Feed amp output to a comparator to make rail-rail signal and drive FET. Lower dissipation. Don't exceed max gate drive. May not look like what you want to see. May. MOSFET in PWM mode - low losses.
Use a linear amplifier to adjust level up or down as required. Can add simple filtering to adjust hang time, attack time, frequency response, more ... . These are all "easy enough" but lets see if this is what you want. MOSFET in linear mode.
... 30PL - slightly better Rdson, slightly more $
Wow!
Infineon IPP065N03LGIN - pricing and datasheet
30V, 50A, 6.5 milliOhm Rdson, 2.7 C/W, TO220
10 milliOhm Rdson worst case at gate drive of 4.5V.
$US1.05/1 in stock.
Looks very good for this task.
It might help if you looked at the safe operating area for the MOSFET in question: -
The X axis is voltage and you can see it is limited to 100 volts. The Y axis is current and this is limited to 140 amps i.e. the "Pulsed Drain Current" specified in the "Absolute Maximum Ratings" table on page 1.
What this tells you is that if you could turn on and off the MOSFET in 10 us you could take 140 amps but with a limited voltage of about 60 volts. That's an instantaneous power of 8.4 kW.
Alternatively you could withstand 100 volts but at a reduced current of about 90 amps. That's an instantaneous power of 9 kW.
This is very much defined as a "single pulse" (bottom left corner of graph) i.e. it is a single event of 10 us.
If your pulse was 10 ms then you could withstand 100 volts whilst taking no more than about 2.5 amps. Notice now that the power taken during this much longer pulse is only 250 watts.
Eventually (if the graph showed this detail) you would find that the continuous power rating of 160 watts means a continuous current of 1.6 amps whilst withstanding 100 volts. Or it could mean 10 amps at 16 volts or 16 amps at 10 volts etc..
What I mean by "OFF" is when the gate voltage is zero (no gate signal)
or when the MOSFET is reverse-biased (i.e. Drain voltage is 0V and
source voltage is +100V).
You can't apply anything more than about a volt in reverse. The body diode in the MOSFET will conduct and, if the reverse supply could provide more than 42 amps, the body diode would break and so would the MOSFET. See "Source-Drain Ratings and Characteristics" for numbers on page 2.
See also this on the last page: -
Best Answer
If you see G,D and S is likely to be a MOSFET, not a BJT. So this is a precious indication and you are very lucky to find it because these markings are very rare. The other good news is that it's 10 years old, not too new and not too old.
Two things you must find out:
The absolute maximum voltage rated for G in the datasheet will likely to be same on every MOSFET you will find. Still, check that it's not lower than 20V (You never know). (always read the datasheet pdf before buying)
Frequency shouldn't be an issue with modern MOSFETs. That's why 10 years old is a good age. Any newer MOSFET will be better than the original, granted that you can find the same specification or better. I would even advise NOT to try to find the exact original part since it failed...
Attention: The same model can be fabricated in different packages: D-PAK or something else but the THT variant is often available. Check the datasheet for the exact product code (the last letters define the package, usually). Don't discard or select a model based on the picture on the vendor website.