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Old 5th March 2010, 04:13 PM   #1021
Salas is offline Salas  Greece
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Lookie! Was remembering wrong. The central conductors are just copper on mine. Stripped one to photo. Its Italian made only thing I know. Got 10 metres from a typical electronics shop once, don't remember for how much, maybe for less than a tenner.
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Old 5th March 2010, 04:18 PM   #1022
Salas is offline Salas  Greece
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Quote:
Originally Posted by sugden View Post
After adding the third parallel 68R to my DCB1:
1. Transformer sec. output= 11.76V
2. After rectification= +14.85V and -14.91V
3. Voltage drop across 3 parallel 68R = 1.552V and 1.670V.
Any comment on all voltage above? I touch the MOSFETs after on for 15min don"t feel hot just a bit warm, i think it ok.
Looks like your Iset Rdrop is getting smaller the lower your Vin-Vout dif. Now you run circa 70mA per rail. Not bad. Is your mains at nominal value if you measure it with DVM on max AC scale? Also how much your row of 3 leds drop?
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Old 5th March 2010, 04:24 PM   #1023
sugden is offline sugden  Singapore
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Quote:
Originally Posted by Tea-Bag View Post
sudgen,
sounds like a nice system.
Thanks Tea-bag, it sound good to my ear. Now start to do something different, DIY some equipment see how far can my system go.
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Old 5th March 2010, 04:39 PM   #1024
sugden is offline sugden  Singapore
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Quote:
Originally Posted by Salas View Post
Looks like your Iset Rdrop is getting smaller the lower your Vin-Vout dif. Now you run circa 70mA per rail. Not bad. Is your mains at nominal value if you measure it with DVM on max AC scale? Also how much your row of 3 leds drop?
My main now AC is 238VAC, after rectification 15V. Row of 3 leds drop = 5.39V and 5.36V.
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Old 5th March 2010, 04:55 PM   #1025
Salas is offline Salas  Greece
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Normal then. Try a listening.
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Old 6th March 2010, 12:03 AM   #1026
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Unhappy sourcing 2sk170 fets

Hi,

I'm looking to construct a B1 myself, but Mouser shows the fets on backorder for 11 weeks? does anyone know of a local (US) source for the 2sk170's?

also, I have 10K noble and 25K alps black beauty pots in my parts bin. which would be better for this application?

thx
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Old 6th March 2010, 12:48 AM   #1027
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You might try Blues over at the swap meet...

Matched Toshiba FETs For Sale

I aquired my matched and unmatched FET's from spencer here on the forums, but he's in Hong Kong. No problems with delivery though, I'm a satisfied customer.

The alps would be easier on the sources I guess, recommended value is 15-25K. I use the LDR attenuator myself, sound is fantastic.
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Old 6th March 2010, 01:35 AM   #1028
udailey is offline udailey  United States
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Hey Tincan
Shoot me your address and I will send you a few 2sk170. Dont anyone else think that one offer is a freebee for everyone. Limited quantity at this low price
Uriah
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Old 6th March 2010, 09:00 AM   #1029
AndrewT is offline AndrewT  Scotland
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Hi Sugden.
The voltage across the current setting resistors should not change. There is slight drift with temperature.

I think your 12Vac transformer is not giving sufficient voltage before the regulator and that's why you see a lower volts drop across the triple 68r, cf. the double 68r.
Do you have a 15+15Vac transformer to try?
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Old 6th March 2010, 11:09 AM   #1030
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Current measurements for my DB1 shunts:

Building a symmetrical psu B1 buffer

also see salas post right after mine.....


Fran
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