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Old 27th June 2008, 06:07 PM   #1331
KSTR is offline KSTR  Germany
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.... I get this response for the drain currents at 20kHz (and no speaker load, exept for those "bypasses" of (100R+100R)//(122R+122R). With 8R load it gets even nastier...

Distortion is accordingly high. BTW I tried cascoding the JFETs and buffering the MOSFET gate drive to lessen some capacitive effects, but to no avail. I'm quite puzzled about that behaviour.

- Klaus
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Old 27th June 2008, 06:57 PM   #1332
EUVL is offline EUVL  Europe
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I don't think we should jijack the F5 thread, so I propose to move the discussion back to Circlomanen's original thread.



Patrick
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Old 27th June 2008, 08:02 PM   #1333
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I have built and tested such a circuit and I'm working on the article now. I will find an appropriate place to publish once finished.
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Old 2nd July 2008, 03:23 PM   #1334
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hi,

i just saw F5 design. wow, very less parts and its easy for me to build.

i have few questions.

Q1 and Q2= can i use IRF9610?
Q3 and Q4 = can i use IRFP240?

is there at output have to place any resister like aleph-3?

how much heat dissipation will be on 50w output? let say i am using 8ohms speaker.

how about the cap for power supply?

thank you
michael
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Old 2nd July 2008, 03:32 PM   #1335
udailey is offline udailey  United States
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Default TH1 TH2

Quote:
Originally posted by Nelson Pass
And the value is not critical at that. I also use 3.3K, because I have
a bag of them.
In regards to TH1 and TH2. I would like to use them. I got some wimpy little thermistors from Digikey.
http://parts.digikey.com/1/parts/indexd12209.html
Pretty concerned that these will melt from more than just temp. Do these thermistors see current? I thought I remembered seeing something about TH1 and TH2 needing to carry 10amps, but maybe this is from the power supply. Cant remember and have not seen that reference again. If someone could give me a bit of help I would appreciate it.
Had my FETs backwards. just found that mistake. Going through P2P again to recheck.
Thanks
Uriah
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Old 2nd July 2008, 03:34 PM   #1336
udailey is offline udailey  United States
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Quote:
Originally posted by space2000
hi,

i just saw F5 design. wow, very less parts and its easy for me to build.

i have few questions.

Q1 and Q2= can i use IRF9610?
Q3 and Q4 = can i use IRFP240?

is there at output have to place any resister like aleph-3?

how much heat dissipation will be on 50w output? let say i am using 8ohms speaker.

how about the cap for power supply?

thank you
michael
Michael, go to http://www.firstwatt.com/downloads/F5-om_sm-080527.pdf and you will have your answers. Last page is PS.
I used the 12,000uf caps from Steve at ApexJr and they are working great. Only $1.99 each. I used 12.
Uriah
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Old 2nd July 2008, 04:54 PM   #1337
Zen Mod is offline Zen Mod  Serbia
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Default Re: TH1 TH2

Quote:
Originally posted by udailey


In regards to TH1 and TH2. I would like to use them. I got some wimpy little thermistors from Digikey.
http://parts.digikey.com/1/parts/indexd12209.html
Pretty concerned that these will melt from more than just temp. Do these thermistors see current? I thought I remembered seeing something about TH1 and TH2 needing to carry 10amps, but maybe this is from the power supply. Cant remember and have not seen that reference again. If someone could give me a bit of help I would appreciate it.
Had my FETs backwards. just found that mistake. Going through P2P again to recheck.
Thanks
Uriah


if these two little buggers ever see some substantial current , then something is definitely wrong ......

just use them and do not worry ; did ya see same critters in Papa's amp ? they are probably same looking .

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Old 2nd July 2008, 05:14 PM   #1338
udailey is offline udailey  United States
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Thank ya Zen
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Old 2nd July 2008, 05:17 PM   #1339
Zen Mod is offline Zen Mod  Serbia
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Quote:
Originally posted by udailey
Thank ya Zen

pleasure is all mine , like always
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Old 2nd July 2008, 07:24 PM   #1340
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Default Couldn't think of a good place to post this.....

The mods can move it if they need to.

For the amplifier builders:

http://www.diycable.com/main/product...roducts_id=598

has a pretty good deal on transformers. This looks like it might work as an F series transformer if run at 240v. Just an idea,

Chris
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