Replacement for 2n3053s,2n4036

[nour]

As in the title, I want an easy to find replacements for those two transistors.

thanks

[3db]

Try Google.

[Kleinstein]

The manufacturers and some distributors have more or less well working parametric search. So one should be able to find a suitable transistor base on the needs of the circuit, or find a source for exactly that transistor. A suitable replacement can depend on the circuit - at least it gets easier to find one if one knows the circuit.

[nour]

I have tried google and Digikey, the problem is this transistor is 5 watt which I couldn't find a direct substitute for it with the same power dissipation level!
Maybe I have used Digikey search in a wrong way

Anyway, this is a pre-stage of a power transistor from output stage in Hp E3631
PSU

I have attached a PDF for this part

[Kleinstein]

My first guess would be BD139/BD140. However they are in a different case and would thus need a different heat sink and bend pins.

Depending on the power dissipation really needed the slightly smaller (3 W) 2N2219/2N2905 might also work.

[2N3055]

As far as I know, you can buy them from Farnell and Mouser...

[nour]

My first guess would be BD139/BD140. However they are in a different case and would thus need a different heat sink and bend pins.

Depending on the power dissipation really needed the slightly smaller (3 W) 2N2219/2N2905 might also work.

I don't actually own the device nor have it on hands, I want to try to build this output stage and try to see how I can use it in my PSU project, I have an open thread talking about other design that folks here said it is not that much great and have some issues, so  I said I may try something else, and what else better than HP E3631 

Anyway, I have viewed the BD139\140 datasheet and they didn't mention anything about the bandwidth\transition frequency? do you have an idea why? the original ones are 100MHZ

[nour]

As far as I know, you can buy them from Farnell and Mouser...

unfortunately, I don't have any fast access to any dealer\distributer other than TME right now which they don't have those parts for now!

[2N3055]

I agree with Kleinstein

BD 139-16 and BD140-16 are your guys..

fT Transition frequency IC=50mA; VCE=5V ;f=100MHz : 190 MHz

-16 means grouping for higher HFE....

You will have to rearrange pins and provide alternative heatsinking.. But it should work same or better...

[Benta]

2N3053 and 2N4036 were popular general purpose parts in the 1970s. There is nothing special about them at all.
For your application, it's uncritical, and BD139/140 are as good a choice as any and much, much cheaper (and freely available everywhere).

[David Hess]

There are a lot of medium power TO-39 transistors that are difficult to find modern substitutes for.  The closest modern parts are in TO-126 and TO-225 packages.

So it looks like we want a complementary pair with:

60 volt Vce
1 amp collector current
5 watt power dissipation at a 25C case temperature
60 to 100 MHz minimum Ft at 50 milliamps
50 to 250 hfe at 150 milliamps

I agree that the BD139/BD140 series should be a good choice.  The Savant datasheets show a typical Ft of 150 to 190 MHz but if you are dubious of that specification, then the 2SA1507/2SC3902, KSA1220A/KSC2690A, and 2SB1143/2SD1683 are suitable also.

If the original TO-39 parts did not need a heat sink, then the above TO-126/TO-225 parts should not require one either but I might mount a tiny free standing U shaped heat sink anyway.

[Cerebus]

Anyway, I have viewed the BD139\140 datasheet and they didn't mention anything about the bandwidth\transition frequency? do you have an idea why? the original ones are 100MHZ

Look at the Op Amps driving them. Their bandwidth is positively slugged by the 2n2 capacitors in the feedback loop (X_c at 100 MHz less than 1 ohm), the Op Amps have a GBW of 3 MHz and it's driving a TIP36C with an F_t of 3 MHz, the base of those transistors will never see anything like 100 MHz. So a high F_t for that transistor is actually a potential liability, inviting instability and self-oscillation.

The BD139/BD140 will do fine here. If anything they are over-specified on the power handling side of things. From memory that transistor only has to sink 30mA (I'm too lazy to dig the schematics out and check) sourced by an LM317 wired as a constant current source. I lied, I'm not too lazy - 39 mA.

[nour]

Anyway, I have viewed the BD139\140 datasheet and they didn't mention anything about the bandwidth\transition frequency? do you have an idea why? the original ones are 100MHZ

Look at the Op Amps driving them. Their bandwidth is positively slugged by the 2n2 capacitors in the feedback loop (X_c at 100 MHz less than 1 ohm), the Op Amps have a GBW of 3 MHz and it's driving a TIP36C with an F_t of 3 MHz, the base of those transistors will never see anything like 100 MHz. So a high F_t for that transistor is actually a potential liability, inviting instability and self-oscillation.

The BD139/BD140 will do fine here. If anything they are over-specified on the power handling side of things. From memory that transistor only has to sink 30mA (I'm too lazy to dig the schematics out and check) sourced by an LM317 wired as a constant current source. I lied, I'm not too lazy - 39 mA.

You know what, I really was thinking the same almost as you said, the opamp ahs a GBW 3MHZ and the TIP36C is also 3 MHZ so why on earth would it make any difference to have 100MHZ preamplifier ?, but I am not that expert and I really just wanted to have a replacement without leaving anything to doubt.
Anyway thanks.

[David Hess]

You know what, I really was thinking the same almost as you said, the opamp ahs a GBW 3MHZ and the TIP36C is also 3 MHZ so why on earth would it make any difference to have 100MHZ preamplifier ?, but I am not that expert and I really just wanted to have a replacement without leaving anything to doubt.

That does not mean that you want to stack up phase delay in every stage.  It is common for the driving transistor to be faster than the output transistor simplifying the frequency compensation and in some cases providing a lower output impedance at higher frequencies.