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Old 29th September 2009, 09:02 PM   #1021
Salas is offline Salas  Greece
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Quote:
Originally Posted by Tea-Bag View Post
I used this one.
512-LM7812CT
I typically buy Fairchild components......
I will order one that works when I get another order to mouser going.
Get a BC517 Darlington along with it just in case your chatter persists, so to know if it is an alternative solution to the extra cap, if you fancy.
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Old 29th September 2009, 09:37 PM   #1022
Salas is offline Salas  Greece
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hey, I don't f$%k around.
From Ferds to Tea, life's a helter skelter ride man.

Who was meditating over piano ballads only, again?
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Old 29th September 2009, 10:30 PM   #1023
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My proto Hypnotize arrived today along with the last lot of components - thanks Tea-Bag - I will try to get it up and running asap.

A question - I have tried measuring / matching the LED's (red ones as per BOM) and they all measure under 1.8v; is it OK to mix LEDs e.g. a Green at 1.96 would get me to the 9.0 requirement? Same would apply to the 5.4volt string. Pity I have no yellow ones!

My 7812 was sourced from Farnell and was made by STElectronics - I will report if it leads to chatter or not.

I was going to try a 12v relay but since I bought a lot of 6v NAiS relays (and sold them on to people) then I will start with the latter.
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Old 29th September 2009, 10:43 PM   #1024
Salas is offline Salas  Greece
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Get a 9V battery and 1k2 resistor. Do that on the pic. Your test Vf is going to be more representative of final use since it simulates 5-6mA.
Mixing is OK. There's no Led problem you can't fix if you do it in the mix
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File Type: jpg Test Vf.jpg (45.3 KB, 616 views)
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Old 29th September 2009, 11:22 PM   #1025
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Teabag: I wasn't looking for you to move to the wiki, just worried that a move had happened and I missed it is all!!

Well done on setting a date. Looking forward to this one!! Fantastic work to you all.

Fran
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Old 29th September 2009, 11:27 PM   #1026
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Quote:
Originally Posted by Salas View Post
Get a 9V battery and 1k2 resistor. Do that on the pic. Your test Vf is going to be more representative of final use since it simulates 5-6mA.
Mixing is OK. There's no Led problem you can't fix if you do it in the mix
Salas - thanks - I had used your suggestion to measure the first few LEDs but having just bought a Peak Transistor tester I was using that to measure the LEDs - its test current varying between 3.3 & 3.5 mA. I will re-measure as per your diagram.

Alan
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Old 30th September 2009, 02:47 AM   #1027
billyk is offline billyk  United States
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Ahhh... Dave Brubeck Take Five, the drum solo... the bass bim, bam, boom, the piano over on the right, and when he hits the tom and the bigger drums the sense of the room just seems to light up with the reverberations, you get the feeling for the size of the studio. Wow.

Last edited by billyk; 30th September 2009 at 02:50 AM.
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Old 30th September 2009, 04:30 AM   #1028
Salas is offline Salas  Greece
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Anybody who is going to physically hold the PCBs is going to maybe feel that this is a very compact & straight made circuit, down to minimal for being a fully functioning discrete preamp with 2 regs. I am happy that you really enjoy it. I hope that will be at least OK for all. Surely it is relatively economical for space and money. No bulky exotic Teflon$ needed.

P.S. Did you restore your CJ tube pre by now? All well?
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Old 30th September 2009, 10:40 AM   #1029
Ian444 is offline Ian444  Australia
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Salas,

A quick question about the power supply if I may, the regulated outputs are fine, but I did a voltage check across R5, the 10 ohm resistor, on the positive and negative regulators. The positive reg has approx twice the voltage across R5 (174mV) as the neg reg's R5 (83mV). Is this normal operation? Just wondering where the extra current is going...

Ian.
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Old 30th September 2009, 02:56 PM   #1030
Salas is offline Salas  Greece
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Certainly to ground, but what kind of idss you used for the K170 next to the strong one? Are your R5 resistors 10R for sure? Also what is your voltage drop across both R1?
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