Transistor substitution question

Hi all,

Can I substitute 2N4403 PDF for 2N4249 PDF in this circuit:

The values look similar but I can't tell if they're close enough for this use.

Thanks,


BTW, did I mention this is a Quad-Eight NS-120 Noise Gate?

I think so if you remember that the 2N4403 is rated for 40 V. BC560C might be more suited here though.

Samuel

You could also use the 2N3904, which is already used elsewhere in the circuit.

jh

3904 is NPN.

Thanks!

Seth,

Quad Eight outbord modules and card amps want to have up to +/- 28 volts, so the total "B+" for the transistors can be up to 52 volts, so it is good to use 60 volts transistors to be safe.

Here is some PNP types you can use for the Q4 transistor:

2N4250A, 60V, note that the 2N4250 with out A is only 40 volts.

BC556B, 65V (NPN= BC546B)

BC640-16, very good PNP small signal driver and " common emitter transistor" for high volt discrete op-amps, 80V 1A 1W in TO-92.
(NPN= BC639-16)

But there ara many small signal PNP transistor on the market that you can use, it it is not any critical application, besides the max voltage.

--Bo

Thanks Bo.

Does this look like a better choice?

Part Number = ECG159
Manufacturer Name = Philips Semiconductors
Average Price = 4.615445
Description = Si PNP LP HF BJT
V(BR)CEO (V) = 80
V(BR)CBO (V) = 80
I(C) Abs.(A) Collector Current = 1
Absolute Max. Power Diss. (W) = 600m
h(FE) Min. Static Current Gain = 180
f(T) Min. (Hz) Transition Freq = 200M
Package = TO-92
Military = N

I have some of these lying around.

Thanks again