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Old 21st January 2013, 11:11 PM   #31
Mr. dB is offline Mr. dB  United States
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Join Date: Dec 2003
Location: Arkansas
Originally Posted by GentryBa View Post
what does "hizzy fit" mean?
It's sort of like a conniption.
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Old 2nd February 2013, 01:19 PM   #32
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Join Date: Oct 2011
Location: Bavaria

@mr. dB:

oh, I see! thank you!

things are going forward on my preamp:
the layout from juma is working fine now, so I was working on the rest of this beast.

- 21 full C-controlled relais to switch in- and ouputs with 7 standard and 14 latching relais.
the 7 takamisawa standard coil relais are powered on for 100ms and setting the 14 latch types to on/off.
the idea is simple: no power on the coils while hearing music!
- you can choose all functions via alps encoder on the preamp or IR-controlled
- motor-controlled volume regulation (it has got four single potentiometers in it, and one I use for the C to get its exact position)
if you switch from tape (my revox B77 tape recorder has got a very small output signal) to cd, the preamp reduces the volume not to destroy the loudspeakers.
you can set up every input with its own volume, or disable this automatic function.

The C also controls the AC-supplys (r-core transformers)and the DC-ones via relais, and every other part in this preamp.

It is too much to tell, in the moment I'm waiting for the aluminium stripes to complete the housing and then sort all the wires and make it look cleaner.

Here a few pics from testing:

C-controlled in/ouput PCB with 21 relais:
Relais PCB for C controlled preamp - My Photo Gallery

testing on my F5 (in the picture you can see only one F5):
C controlled preamp for F5 - My Photo Gallery

chaotic, but I wait for the housing:
C controlled preamp for F5 - My Photo Gallery

best regards,
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Old 14th October 2015, 07:55 PM   #33
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Join Date: Jul 2012
Location: germany
hello at all, i want also build the juma pre, but i want build the power supply with some "superegs". How can i make the pre power supply which must have 40 volt or so. The 317/337 seemed not practicable. Or can the +-33 volt changed to 27-30 volt or so? +-24 volt for the buffer is no problem. any opinions? i stay tuned.
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Old 16th October 2015, 02:46 PM   #34
AndrewT is offline AndrewT  Scotland
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Join Date: Jul 2004
Location: Scottish Borders
The 317/337 are limited to a maximum Vin-Vout difference of ~40V.
Read the datasheet again.

If you protect the reg IC at start up, then you can run the 317/337 at very high voltage.
regards Andrew T.
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