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Old 6th November 2010, 11:24 PM   #601
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Quote:
Originally Posted by AndrewT View Post
do you mean that the CCS sets the current draw for the regulator circuit, or do you mean how to set the CCS current draw?
hmm, what I mean, is how is the 300ma current set.
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Old 7th November 2010, 09:18 AM   #602
AndrewT is offline AndrewT  Scotland
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look at a standard two BJT transistor CCS.
The resistor in the supply route has a Vbe across it from the control transistor.

The pass transistor is controlled by that second transistor.

A BJT has nearly constant Vbe over a wide range of Ic. This allows the resistor that is parallel to Vbe to see a nearly constant voltage and thus pass a nearly constant current.

The resistor sees a voltage and passes a current based on Vbe / R, eg. 620mV/ 220r ~ 2.8mA

The FET type CCS works the same way.
The resistor sees a nearly constant voltage and the FET passes that constant current to the load.
In the SALAS style, the voltage across the resistor is not from a second transistor.

The resistor voltage comes from the Vgs of the FET and the Vf of the LED string. Vgs of a FET is substantially constant over a wide range of Id.
Current is defined by [Vfleds-Vgs] / R, eg [(1.8*3)Vfleds-4.1Vgs] / 33ohms = 1.3/33 ~ 0.039A = 39mA

The supply transformer+rectifier+smoothing caps sees a near constant load of ~39mA + [the current through the LED string that runs initially parallel to the setting resistor and then to Ground].
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Last edited by AndrewT; 7th November 2010 at 09:20 AM.
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Old 8th November 2010, 12:59 PM   #603
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Nearly finished my DCB1, just waiting for a few bits.

Salas - is it ok to use 2R resistors in place of the 2 x 1R?

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Old 8th November 2010, 02:45 PM   #604
Salas is online now Salas  Greece
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Yes, its OK.
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Old 9th November 2010, 03:48 PM   #605
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Are these the right size for the PS section?

4700uf / 63VDC, MLytic® Audio Grade Snap-In, 30mm x 40mm

I'm going to order a few...
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Old 9th November 2010, 03:54 PM   #606
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Quote:
Originally Posted by merlin2069er View Post
Are these the right size for the PS section?

4700uf / 63VDC, MLytic® Audio Grade Snap-In, 30mm x 40mm

I'm going to order a few...
They are still too big. The caps need to be 25mm max diameter. You need the 40V version of those caps, if you can find them.

Unless you are absolutely commited to having Mundorf caps, Can I recommend the 4700uF / 63V, Nichicon KG Series, Gold Tune, 25x50 from PX:

https://www.partsconnexion.com/capac...chicon_kg.html

Or Panasonic TSUP are excellent PS caps.
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Old 9th November 2010, 04:03 PM   #607
Nick77 is offline Nick77  United States
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Isnt this Mundorf cap at partsconnextion a good fit?

https://www.partsconnexion.com/capac...rf_snapin.html


MUNDORF-71841

4700uf / 40VDC, MLytic® Audio Grade Snap-In, 22mm x 30mm, 68 ESR (mOhm) 10 ESL(nH)
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Old 9th November 2010, 07:01 PM   #608
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I bought antek's 0512 transformers for my older (not blue edition) dcb1 buffer. I was going to use them for my blue edition, but I don't think they can power the blue edition buffers.
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Old 9th November 2010, 07:09 PM   #609
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Quote:
Originally Posted by merlin2069er View Post
I bought antek's 0512 transformers for my older (not blue edition) dcb1 buffer. I was going to use them for my blue edition, but I don't think they can power the blue edition buffers.
depends on what kind of current your going for.
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Old 11th November 2010, 02:38 PM   #610
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Default Omron G6H-2 12VDC relays

Greets,

In support of stuffing these boards I have started an interest thread in the Swap Meet to supply the Omron G6H-2 relays. Express your interest there.

It appears there is sufficient stock currently available. However they are no longer being produced.

Omron G6H-2 12VDC relays

Thanks for all
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