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OLD THREAD Simplistic Mosfet HV Shunt (The Simpler Simplistic Design by Salas)

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#249
Simple question: on the instructions of the board it looks like I am supposed to use a transformer NOT CT, but the board has three connection for transformer wire. I understood that the board include a bridge rectifier. What type of transformer should I use ? How to connect it ?

I saw the questions on the DAC GB, but they are even more confusing.

Thanks,


Davide
 
#251
Nikon1975 said:
Simple question: on the instructions of the board it looks like I am supposed to use a transformer NOT CT, but the board has three connection for transformer wire. I understood that the board include a bridge rectifier. What type of transformer should I use ? How to connect it ?

I saw the questions on the DAC GB, but they are even more confusing.

Thanks,


Davide
Click to expand...

Populate only D10 and D12 and you can use a CT transformer. Leave D9 and D11 unpopulated.

If you use bridge rectifiers (for a transformer without CT), populate all D9 - D12, connect the 2 HV leads of the transformer to the 2 AC pads (the CT pad should not be connected!).
 
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#252
As pointed out by dodo, the pads of the PCB are neither tinned nor gold-plated. So it's wise to tin-plate the pads with a solder gun manually to prevent future oxidation of the copper pads whenever possible. 😀
 
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#253
Look! Look!

My partially populated PCB, all pads tin-plated. 😀
 

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#255
Housing, thanks for the reply !



Another question: looking at the instructions, D1 is a 1N383B 150V 5A diode.

Is it correct ? I cannot find this component. Even if I google 1N383B I do not get anything.

5A ? Isn't a bit too much ?

Additionally, I am using the Solen Fastcap 1uF capacitors (630V) is this a good choice ?

Thanks,

Davide
 
#256
Nikon1975 said:
Housing, thanks for the reply !



Another question: looking at the instructions, D1 is a 1N383B 150V 5A diode.

Is it correct ? I cannot find this component. Even if I google 1N383B I do not get anything.

5A ? Isn't a bit too much ?

Additionally, I am using the Solen Fastcap 1uF capacitors (630V) is this a good choice ?

Thanks,

Davide
Click to expand...

You're welcome. In fact D1 is a 5 watt zener diode 1N5383B. It's there for protection of the IRF9610.

1n5383b

If you already have the Solen, whether it's good or not so good, there's no harm to use it. The most important thing is to make the shunt regulator work first. Try other caps afterwards to see if they work better or not.
 
#258
Nikon1975 said:
Simple question: on the instructions of the board it looks like I am supposed to use a transformer NOT CT, but the board has three connection for transformer wire. I understood that the board include a bridge rectifier. What type of transformer should I use ? How to connect it ?

I saw the questions on the DAC GB, but they are even more confusing.

Thanks,


Davide
Click to expand...

yes you can use CT for the supply. no problem. but need 2 diode!
 
#259
Nikon1975 said:
Thanks,

And I guess D1 is mounted off board, just between the pins of the IRF9610.
In case I cannot find 150 V, can I use two 75 V in series ?

D.
Click to expand...

Don't put that there yet because Quanghao reported problems with it in his former layout. Let it work first without it, so you know it does OK, and if you got a spare mosfet in case it kills, put a single 150V 5A one if you find, straight underneath, short legs, with its anode on drain and cathode (stripe) towards source & Rset. If it kills for some reason, change mosfet and forget. Works in my build perfectly, works in two simulators also, but who knows in another layout or with two in series.
 
#260
Good idea the wiki !

I went through all the thread of the development, and I took some notes of things that can be useful. First thing is a table Current vs value of R1.

My question is: is this universal, or it depends on the voltage that you have on the leds ?

I wanted also to propose a draft for a step by step design and tuning. The goal would be a guide to determine:
A) If you have to use the High or low voltage version.
B) The voltage and current of the transformer in case of CT or not CT.
C) The value of R1.
D) The approx value of R8
E) Determine the heatsink requirements.
..I try, please correct me, when we have a good version we put it on the wiki:

1) Determine operating voltage (Vload) and max load current (Iload).
2) If Vload>300 V
Q2=MPSA94
R3= 82K/5W
R4=220K/2W
If Vload< 300 V
Q2=MJE350
R3=56K/5W
R4=120K/2W
3) Iload+25mA < Iccs < 2 * Iload

Vload + 25 V < Vccs < Vload + 50V

(higher values of Iccs and vccs improve performances, but increase the heat production, I would start with a minimum needed difference between Iload and Iccs and vccs)

4) Make a first estimate of R1 using the following table
Iccs=40mA >>R1=56R/1W
Iccs=50mA >>R1=47R/1W
Iccs=60mA >>R1=33R/1W
Iccs=80mA >>R1=22R/1W
Iccs=100mA >>R1=20R/1W

5) Use PSU2 to determine the AC voltage needed considering the chosen topology of the filter.

6) Set the trimmer R8 to 500 ohm

7) connect as dummy load a 15K/20W resistor (Note: I think this has to be increased in extreme applications)

8) connect two voltmeters, set on DC, one on the dummy load and one on R1.

9) power the circuit

10) with extreme care, and the left hand behind your back, adjust the output voltage to Vload.

11) Note the voltage Vr1 measured on R1 (should be in the range of few volts). The real Iccs can be calculated Iccs=Vr1/R1

Next post the notes on the heat dissipation.

PLEASE NOTE THIS IS A DRAFT, DON'T TAKE IT AS INSTRUCTIONS UNTIL IS NOT CORRECTED !!

Hope this helps,

Davide
 
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