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Old 20th February 2013, 02:21 PM   #141
Elvee is offline Elvee  Belgium
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Quote:
Originally Posted by abetir View Post
Sir Elvee,
Can a TO-3 darlington transistor also be used on the Circlophone?
A friend of mine had MJ2500 (TO-3), I was thinking of using them on this amp.
It looks possible: Terranigma has asked the same question, and I gave an example circuit here (tested in sim only):
♫♪ My little cheap Circlophone© ♫♪
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♫♪ My little cheap Circlophone© ♫♪
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Old 20th February 2013, 02:47 PM   #142
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I'm building a darlington circlophone following Elvee's example circuit mentioned above. I think it is going to be first darlington build. By considering your requirements, MJ2500 is out of spec. It is PNP and Vceo is 60V according to Motorola datasheet. Our circuit implies NPN power darlington has at least 2*Vs Vceo. You have to look for NPN type output devices at least 100V Vceo according to your 45V rails.
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Old 20th February 2013, 04:15 PM   #143
Elvee is offline Elvee  Belgium
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It would be possible to use a P-darlington as a drop-in replacement for each CFP.
The B-E resistor just needs to be raised to 120ohm, like here:
♫♪ My little cheap Circlophone© ♫♪
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Old 20th February 2013, 11:17 PM   #144
abetir is offline abetir  Philippines
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Quote:
Originally Posted by terranigma View Post
I'm building a darlington circlophone following Elvee's example circuit mentioned above. I think it is going to be first darlington build. By considering your requirements, MJ2500 is out of spec. It is PNP and Vceo is 60V according to Motorola datasheet. Our circuit implies NPN power darlington has at least 2*Vs Vceo. You have to look for NPN type output devices at least 100V Vceo according to your 45V rails.
Whoops my bad, yep I have corrected that I have inter-mixed pnp to npn while describing the circlophone to him, actually he was puzzled when he mentioned to me the MJ2500 he had...

Nice to know that you will be creating a Darlington version.

TY!
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Old 11th March 2013, 11:01 AM   #145
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Quote:
Originally Posted by Piersma View Post
hi all,

All the Circlophone (Complementary Feedback Pair) PCB documents.
Final board revision.

enjoy!
Hello! I am currently working on this particular model, but am having a bit of an issue. The resistor in the middle of the board - the one surrounded by the coil - is having its value blocked. I cannot see what it says. I think it is R17 on the original schematic, which is rated at 10K. Is this correct? On the board, it kinda looks like it says 10/3W, as in, just 10R. This is making me confused.

Thanks everybody, for all of this. Very exciting thing, this Circlophone.
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Old 11th March 2013, 11:35 AM   #146
Elvee is offline Elvee  Belgium
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Quote:
Originally Posted by Welcome View Post
I think it is R17 on the original schematic, which is rated at 10K. Is this correct? On the board, it kinda looks like it says 10/3W, as in, just 10R.
It is 10R (non-critical)
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Old 14th March 2013, 07:18 AM   #147
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Hi again! I'm still working on Piersma's CFP circuit. But I have some more questions.

Click the image to open in full size.

1. What is the value of this resistor? On Piersma's picture, I can see that there's a resistor here, rather than a jumper, which I originally assumed the 000 ohm designation meant. I cannot see the value of it, though, as the picture is too low res.

2. I assume these unmarked diodes are supposed to be 1N4148, but I would like to make sure, just in case.

3. I do not have 11K5 resistors. Would 12K be okay to use here?

4. Is this coil critical? It says 22 turns, but what else do I need to keep in mind? Wire thickness? Coil diameter?

Sorry for all this. I'm learning! Thanks for reading.
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Old 14th March 2013, 09:10 AM   #148
Piersma is offline Piersma  Netherlands
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Default New PDF

hi Welcome,

I will make a new PDF file, that will answer all you questions.
Give me a day or two.

regards,
Piersma
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Old 15th March 2013, 02:35 AM   #149
abetir is offline abetir  Philippines
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I just hope that it is as close as to this one...coz' I have etched the board....
Attached Files
File Type: pdf CFP Circlophone assembly.pdf (54.2 KB, 81 views)
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Old 15th March 2013, 09:28 AM   #150
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Originally Posted by Piersma View Post
The silkcreen of CFP Circlophone states in post #96 by mistake that the phase inverter is the PNP 2SA1209. This should be the NPN 2SC2911.
For your information, the attached PCB lay-out in post #96 is correct and tested.
I somehow missed this when ordering parts... And now I cannot for the life of me find a 2SC2911 anywhere. What other transistors could I use here? Would BD139 work? I'm going to be using a +/-30V supply.

Thanks again.

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