which mosfet can i use instead of..

[wavenator]

ok i have this scheme

can i use instead of this 2sk1058
for example IRF520
cause i cant get any of those sk's

[wavenator]

someone?

[George Giblet]

The IRF520 is by no means an equivalent but by my calculations it should work in that circuit.   The IRF520 will have more gain.

Soundwise I cannot comment on how similar they will be.

You *MUST* mount the MOSFET on a heatsink.   I'd go for a heatsink with a thermal resistance of 5 degC/W and would cringe at anything more than 10degC/W.

[wavenator]

oh trust me heatsinks is my professionality
i am an overclocker(if you know what it means)
all my room is full of heatsinks

[wavenator]

btw one more question
the 15R
      40W
where can i find a 40 watt resistor
whats this 15r means?

[Gus]

12 volts / 15 ohms = 4/5 = .8 amps, 15r most likely means 15 ohms

DC power = voltage x current = 12VDC x .8amps = 15watts dissipated by the mosfet at idle.

What are the specs of the IRF520?

Be careful with the 100k bias setting some mosfets fail at 20VDC gate to source

You might have a rolled off high end because of the gate capacitance of the mosfet working with the series resistors(1K and part of the volume control) you would want a low output resistance drive before this circuit

[ambulancevoice]

15r is 15 ohms
i found these
if you put them in series with each other, they should get 15 ohm and are more than enough wattage
http://cgi.ebay.com/5-Ohm-50-Watt-Power-Resistor-Tunnel-Case-Ohmite_W0QQitemZ350055089236QQcmdZViewItem?hash=item350055089236&_trksid=p3286.m14.l1318
http://cgi.ebay.com/10-Ohm-50-Watt-Power-Resistor-Tunnel-Case-Ohmite_W0QQitemZ350055087907QQcmdZViewItem?hash=item350055087907&_trksid=p3286.m14.l1318

to be honest i wouldnt bother building this
it uses unusual or rare/htf parts, and no body else (that i know of) has even built this thing, so who knows if it even works???

[wavenator]

it works
people have already built this one

anyway
isnt there any other option to pass this 40w resistor
i really cant get any one of those

btw if i put this resistor out
and i supply this circle a 12 volt
it will work properly?

[George Giblet]

From what I can work out the original article uses four 15 ohm 10W resistors.  I can imagine you wire them like so:  parallel up two 15ohm resistor, make two of these networks, then wire these two pairs in series with each other.  Each pair is a 7.5ohm 20W resistor, and putting them in series gives you 15ohm at 40W.

[wavenator]

yea now i can see
well this is good

anyway
ill ask the last time

can i use IRF530 instead of 2sk1058?