Re: To increase your power you will need some small modifications
Hi Carlos,
thanks for your help in the 50Volt version.
I do not understand what you mean by ".... also you can use two BD139 as VAS".
Does this mean that I should use a transistor such as the MJE15032 instead of the BD139?
Also do I increase the 1K5 resistor that connects the positive rail to the 47uF cap?
Regards
Harry
destroyer X said:
Hi Carlos,
thanks for your help in the 50Volt version.
I do not understand what you mean by ".... also you can use two BD139 as VAS".
Does this mean that I should use a transistor such as the MJE15032 instead of the BD139?
Also do I increase the 1K5 resistor that connects the positive rail to the 47uF cap?
Regards
Harry
Just a small bit of feedback.
Today nothing much got done as I had to go to a medical specialist again. I did however rent the webserver this morning, but I am still battleing with the domain... registrar is haveing a problem with the nameserver... hope to have this resolved by tommorrow, as the website is nearly done.
Today nothing much got done as I had to go to a medical specialist again. I did however rent the webserver this morning, but I am still battleing with the domain... registrar is haveing a problem with the nameserver... hope to have this resolved by tommorrow, as the website is nearly done.
The voltage amplifier stage is using two transistors
one is small, and the second one is bigger (BD139)...i said that both can be BD139...those two transistors, together, constitute the VAS, the voltage amplifier.
All the voltage produced into the amplifier appear there.
The VAS stage, normally second stage, receive the signal from the first transistors into the differential..into the colector you may have a resistance or a transistor as a load for the first transistor.... transconductance happens there...current appear and will send to the VAS... this will be magically transformed into enormous voltage swing...more than 50 volts peak to peak.
............................
The amplifier has no noises into turn on or turn off..silent..dead silent.
regards,
Carlos
one is small, and the second one is bigger (BD139)...i said that both can be BD139...those two transistors, together, constitute the VAS, the voltage amplifier.
All the voltage produced into the amplifier appear there.
The VAS stage, normally second stage, receive the signal from the first transistors into the differential..into the colector you may have a resistance or a transistor as a load for the first transistor.... transconductance happens there...current appear and will send to the VAS... this will be magically transformed into enormous voltage swing...more than 50 volts peak to peak.
............................
The amplifier has no noises into turn on or turn off..silent..dead silent.
regards,
Carlos
Ok guys the domain www.dxamp.com is now live....
I have started to upload the information, but managed to break my template again... got it mostly fixed as I type this... so some pages are available, others will be unavailable for a few minutes as I work through them...
Orders are not active yet, as I am still waiting for authorisation to get a credit card facility.
Also the construction aids have not been uploaded yet, as I still need to do the artwork for that.
You can get a general feel for how things will work and what will be required, by going through the site so long.... there will be many typo's and things like that over the next day or two... I run the spell checker when I'm happy that I am more or less done.
I have started to upload the information, but managed to break my template again... got it mostly fixed as I type this... so some pages are available, others will be unavailable for a few minutes as I work through them...
Orders are not active yet, as I am still waiting for authorisation to get a credit card facility.
Also the construction aids have not been uploaded yet, as I still need to do the artwork for that.
You can get a general feel for how things will work and what will be required, by going through the site so long.... there will be many typo's and things like that over the next day or two... I run the spell checker when I'm happy that I am more or less done.
Hi All
I'm excited to get started on this!
A question:
Is there a rock-solid trustworthy supplier in the US for the Toshiba output transistors? I've been hearing so much about fakes, and have got really concerned about this.
TIA
Andrew
I'm excited to get started on this!
A question:
Is there a rock-solid trustworthy supplier in the US for the Toshiba output transistors? I've been hearing so much about fakes, and have got really concerned about this.
TIA
Andrew
MCM Electronics carries some Toshiba devices. Don't know if they have what you're looking for or not.
http://www.mcmelectronics.com/
http://www.mcmelectronics.com/
Thanks Kaos, they do have them, 2SA1943 and 2SC5200 are $5.29 and $3.99 ea respectively. Are these guys 100% trustworthy?
I've never had any problems, and I've bought a fair number of Toshiba parts from them over the years.
http://www.ampslab.com/trans_2sc5200.htm
sells 5 complementary pairs of sc5200 and sa1943 for $35, you need 1 pair per channel, sure it won't be hard finding someone to share an order with...
sells 5 complementary pairs of sc5200 and sa1943 for $35, you need 1 pair per channel, sure it won't be hard finding someone to share an order with...
Just to give you an idea of the price, I phoned the official Toshiba destributors quickly.... prices qouted in south african rand (ZAR)
sc5200 single R110, tube of 100 R18 each
sa1943 single R92, tube of 100 R16 each...
So even if you bought 100, the price comparison would be
5x18 + 5x16 = R170 (but you have to buy R3400 worth of transistors)
$35 = +-R240
So I think that $35 price is pretty fair.
sc5200 single R110, tube of 100 R18 each
sa1943 single R92, tube of 100 R16 each...
So even if you bought 100, the price comparison would be
5x18 + 5x16 = R170 (but you have to buy R3400 worth of transistors)
$35 = +-R240
So I think that $35 price is pretty fair.
How is their international shipping rates... I just happened to see the digikey price for these this morning.... pretty good.
Hey guys, some news...
I uploaded the first of the construction documents like, PCB, silkscreen, and schematic, for the amp today.
I also received the test merchant account, for setting up the orders page today, hope to have a shopping cart installed and running, shortly.
I uploaded the first of the construction documents like, PCB, silkscreen, and schematic, for the amp today.
I also received the test merchant account, for setting up the orders page today, hope to have a shopping cart installed and running, shortly.
Ok, I looked at Farnell, they charge GBP2.5 per...
We can get that through manthech on special order... they add a bit to the price, but it is normally not too much.
PS... will someone do me a favour, I seem to be stuck behind a cashe, just go to the construction help page on the site, and see if you can open all the pdf's that have file sizes indicated... the other ones are not linked to anything yet...
I can see the files in my ftp browser, but IE won't open all of them.
Giving me gray hairs...
P.S. I know its still a little crooked in Firefox... working on it.
We can get that through manthech on special order... they add a bit to the price, but it is normally not too much.
PS... will someone do me a favour, I seem to be stuck behind a cashe, just go to the construction help page on the site, and see if you can open all the pdf's that have file sizes indicated... the other ones are not linked to anything yet...
I can see the files in my ftp browser, but IE won't open all of them.
Giving me gray hairs...
P.S. I know its still a little crooked in Firefox... working on it.
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