Danyele, what is your intended purpose for that transistor? It would be a help answering your question, knowing that.🙂
Steen.
Steen.
steenoe said:
The MPSA18 in aleph it is used to polarize the output transistor.
The BC550B it's ok?
You can order MPSA18 directly from Fairchild. Just go to the Fairchild website and search for MPSA18. The rest is obvious. For sure no fakes, and very good price. Higly recommended.
Patrick
Patrick
I do not know if I should say this, but 😀 You can order them as samples from Onsemi as well🙂 Topclass components, no fakes whatsoever. You have 10 (yes ten) orderlines to fill out with your wishes. Just like Christmas, I guess🙂 Be sure to order a few Mur's as well, they come in every flavour🙂 And ofcourse the not so new anymore MJL4281A and MJL4302A with their drivers too ofcourse🙂 I better stop now, Guess I am shooting myself in the foot😀 It will all in all cost you the royal amount of 14,99$ They also have some nice JFet's and voltage regulators and........ Now I really have to stop😀 😀 😀
Steen.
You might take a look at the Zetex ZTX-450. Nelson seems to like to use them in amps such as the Aleph 60. A more modern up to date replacement for the workhorse MPS series.....
Mark
Mark
BC550B or C work fine. I´ve used them in my Aleph5 and Aleph-X. You only have to turn them 180° because of the pin layout. cbe instead of ebc
William
William
Factor of 2 noise difference between MPSA18 and BC550 according to data sheet (both Fairchild). For ZTX450 noise is not quoted. Also MPSA18 has much higher hfe than BC550 on average.
Of course you can argue that noise does not matter in the Aleph current source given enough gain. Matter of opinion.
But both works as you said (speaking from own experience).
Patrick
Of course you can argue that noise does not matter in the Aleph current source given enough gain. Matter of opinion.
But both works as you said (speaking from own experience).
Patrick
According to Fairchild data sheet
hfe BC550C 110 -- 800
hfe MPSA18 500 -- 1500
My own experience (min. 50 each, measured values) :
hfe BC550C around 500
hfe MPSA18 around 850
All from Fairchild.
Patrick
hfe BC550C 110 -- 800
hfe MPSA18 500 -- 1500
My own experience (min. 50 each, measured values) :
hfe BC550C around 500
hfe MPSA18 around 850
All from Fairchild.
Patrick
I have some original mpsa18 from Onsemi, they measure all about
hfe = ~1000, vce = 5v ! I doubt you can easily substitute these...
(If this high hfe is necessary)
Mike
P.S. Is it me, or is Onsemi's sampleprogram supplying half of the DIY-fanatics ?
hfe = ~1000, vce = 5v ! I doubt you can easily substitute these...
(If this high hfe is necessary)
Mike
P.S. Is it me, or is Onsemi's sampleprogram supplying half of the DIY-fanatics ?
> P.S. Is it me, or is Onsemi's sample program supplying half of the DIY-fanatics ?
You get 5 samples, once, for US$15 shipment charges, unless you order something else -- hardly a bargain. And suppose you want to build 2 Aleph X. You would need 4. So only 1 extra, hardly enough if you want to match Vbe and hfe.
Of course you might have luck and they are all perfectly equal from the 5 samples.
Still, I am not complaining. I like samples too. But I like direct purchase even more. Like if you want to get 30 pieces MJ15003's, the only 'safe' source is Farnell for ca. 5 Euros per piece. Or digikey, paying 20 Euro for shipment, ......
Patrick
You get 5 samples, once, for US$15 shipment charges, unless you order something else -- hardly a bargain. And suppose you want to build 2 Aleph X. You would need 4. So only 1 extra, hardly enough if you want to match Vbe and hfe.
Of course you might have luck and they are all perfectly equal from the 5 samples.
Still, I am not complaining. I like samples too. But I like direct purchase even more. Like if you want to get 30 pieces MJ15003's, the only 'safe' source is Farnell for ca. 5 Euros per piece. Or digikey, paying 20 Euro for shipment, ......
Patrick
I also prefer buying, but for parts hard to get ?
And if you once pay 15$, i ordered as hell, 25 pieces of each.
Felt a bit guilty afterwards... All shipments were from singapore,
using UPS-express, every transistortype extra...
Makes shipmentcosts of ~50$ each.
And if you once pay 15$, i ordered as hell, 25 pieces of each.
Felt a bit guilty afterwards... All shipments were from singapore,
using UPS-express, every transistortype extra...
Makes shipmentcosts of ~50$ each.
BC550 from Philips also has an average hfe of around 500 (25 samples measured).
They also have a noise figure of 4dB, compared with 2dB for MPSA18 from On Semi under same conditions and bandwidth.
But there is no point in arguing. Take whatever you fancy, MPSA or BC or Zetex or 2SC2240, or better still MAT02 wired in parallel.
Patrick
They also have a noise figure of 4dB, compared with 2dB for MPSA18 from On Semi under same conditions and bandwidth.
But there is no point in arguing. Take whatever you fancy, MPSA or BC or Zetex or 2SC2240, or better still MAT02 wired in parallel.
Patrick
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