How about substituting some MPS8099/MPS8599 transistors for the BC550C/BC560C? The BC devices are proving difficult and/or expensive to source in the small quantity (3 pairs) needed.
However, my trusty parts box has produced 3 pairs of the MPS8099/MPS8599 and they all measure an Hfe of ~200 (with my meter). But the "C" in the BC devices indicate an Hfe range of 420-800. Otherwise most of the specs for the MPS devices are very similar to those of the BC devices.
What do you guys think? Are the MPS8099/MS8599 transistors close enough to use in place of the BC550C/BC560C? I'm not looking for perfection here, just a working amp that sounds good.
Thanks for your help 🙂 .
However, my trusty parts box has produced 3 pairs of the MPS8099/MPS8599 and they all measure an Hfe of ~200 (with my meter). But the "C" in the BC devices indicate an Hfe range of 420-800. Otherwise most of the specs for the MPS devices are very similar to those of the BC devices.
What do you guys think? Are the MPS8099/MS8599 transistors close enough to use in place of the BC550C/BC560C? I'm not looking for perfection here, just a working amp that sounds good.
Thanks for your help 🙂 .
Hi Dick
You have to ask what is the circuit need for the "C" grade of BC550/560 as the four have similar minimum gains. There may be a reason for Hfe of 420-800 rather than 200. It could be a base bias restriction, or a stability consideration.
You have to ask what is the circuit need for the "C" grade of BC550/560 as the four have similar minimum gains. There may be a reason for Hfe of 420-800 rather than 200. It could be a base bias restriction, or a stability consideration.
MPSA56/06 too (aren't these the substitutes that Dr. Leach had recommended?)
sometimes the MPS8599 are difficult to latch onto -- they are on 6 week backlog at the moment. MPS8099's can be had anywhere.
sometimes the MPS8599 are difficult to latch onto -- they are on 6 week backlog at the moment. MPS8099's can be had anywhere.
Thanks to everyone for their comments. I also had an opportunity to confer with a consulting EE (not a member here). We compared Vcbo, Vceo, Vebo, Ft, etc. , and concluded that the MPS and BC devices are very similar with major specs being almost identical -- except for Hfe. He couldn't offer an opinion about the need for high Hfe BC devices when they are used in cascode with MJE340/350 devices. Anyway, he said "go for it" with the caveat the final product be checked with an o'scope for oscillation (a good recommendation for any amp project).
Cheers........🙂
Cheers........🙂
MPS8099/MS8599 is similar but with different pinout and much worse current gain, which probably isn't any problem but you may have to change some passive parts.
If you really want BC550C and BC560C I have lot's of them. Send me a message if you want some.
If you really want BC550C and BC560C I have lot's of them. Send me a message if you want some.
The easiest and probably most reliable sources for BC550C and BC560C (or whatever else version) are in my opinion :
Fairchild Direct (just order 100 each and pay by credit card)
or Sample request from On Semi (limited to 25 pieces each, but you can order up to 10 semiconductor types for US$15, again credit card).
Have tried both. Very satisfied customer. And for sure no fakes.
Patrick
Fairchild Direct (just order 100 each and pay by credit card)
or Sample request from On Semi (limited to 25 pieces each, but you can order up to 10 semiconductor types for US$15, again credit card).
Have tried both. Very satisfied customer. And for sure no fakes.
Patrick
EUVL,
I considered getting 100 each of the two devices needed and out of the 200 I should be able to extract sufficient number of matched pairs. Then, what do I do with the remainder?
Two hundred transistors at around $0.35@ would cost me $70 US. How much to buy 2 or 3 matched pairs? Do you want to sell me 3 matched pairs, matched at around 10% in the 550 Hfe range? How much for them?
I have gotten samples before but how large a group of devices would I need to extract matched pairs?
I don't disagree with you but so far do not think it is an economical way to get the handful of required parts. I am waiting to hear from Peranders who may have my solution. If he doesn't, perhaps you do?
Thanks.......
I considered getting 100 each of the two devices needed and out of the 200 I should be able to extract sufficient number of matched pairs. Then, what do I do with the remainder?
Two hundred transistors at around $0.35@ would cost me $70 US. How much to buy 2 or 3 matched pairs? Do you want to sell me 3 matched pairs, matched at around 10% in the 550 Hfe range? How much for them?
I have gotten samples before but how large a group of devices would I need to extract matched pairs?
I don't disagree with you but so far do not think it is an economical way to get the handful of required parts. I am waiting to hear from Peranders who may have my solution. If he doesn't, perhaps you do?
Thanks.......
a) These are so general purpose that you'll always find some use. I must have used 50 out of the 100 by now.
b) 25 samples from On-Semi should probably give you 3 pairs of each type easy. Hfe does vary between complementary pairs so one needs luck, like everyone else. But if you have 10 types of semiconductor to order (power transistors, logic chips, diodes, even regulators, .... ), On Semi is bargain.
c) I do not use them for amplifying (I used MPSA18, also from On Semi), and I do not use complementary, so I have no matched complementary pairs on hand. And I doubt anyone would want to offer complementary pairs for money because it is a lot of work and the items are low value. But maybe peranders or other DIYers can help you with matched pairs.
Patrick
b) 25 samples from On-Semi should probably give you 3 pairs of each type easy. Hfe does vary between complementary pairs so one needs luck, like everyone else. But if you have 10 types of semiconductor to order (power transistors, logic chips, diodes, even regulators, .... ), On Semi is bargain.
c) I do not use them for amplifying (I used MPSA18, also from On Semi), and I do not use complementary, so I have no matched complementary pairs on hand. And I doubt anyone would want to offer complementary pairs for money because it is a lot of work and the items are low value. But maybe peranders or other DIYers can help you with matched pairs.
Patrick
To Dick and others : Is funny to see crying of poor guy from rich country and see his searching for free samples 😀 . BC ... cost cca 5 cents, not 0.35 USD. Electronic hobby, like all hobby, something cost and nothing is in our world free. Take it or leave it, instead of this commodity you can " hunt " butterly, it is still free.
For the record,
Samples from On Semi cost US$15-, far from "free" if you just want a few BC550s / BC560s.
"Fairchild Direct" is direct PURCHASE, i.e. you pay for anything you care to want, only direct from Manufacturer.
I use both because this is the ONLY way that I am sure the parts are from those manufacturers. And I do not feel guilty at all about using those channels again. In fact, I would love to be able to direct purchase from all other manaufacturers like Toshiba or Hitachi, or else, EVEN I can get them elsewhere at lower costs.
And I do not have a problem if people, from whatever country, try to save money in pursuing their hobbies. Just look at how many group buys there are on the forum. Not that I have joined ANY.
Patrick
Samples from On Semi cost US$15-, far from "free" if you just want a few BC550s / BC560s.
"Fairchild Direct" is direct PURCHASE, i.e. you pay for anything you care to want, only direct from Manufacturer.
I use both because this is the ONLY way that I am sure the parts are from those manufacturers. And I do not feel guilty at all about using those channels again. In fact, I would love to be able to direct purchase from all other manaufacturers like Toshiba or Hitachi, or else, EVEN I can get them elsewhere at lower costs.
And I do not have a problem if people, from whatever country, try to save money in pursuing their hobbies. Just look at how many group buys there are on the forum. Not that I have joined ANY.
Patrick
I agree. You and a couple of others here have helped me better understand how to source parts. Thanks.....😉
Guys, these types of transistors are absolutely standard product and is quite free, which is manufacturer. You can buy it in every stores with devices, price is typicaly 5 cents, 100 pieces is price of one " Big Mac ", I think. 😉
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