Salas hotrodded blue DCB1 build

[AndrewT]

It works.

remember to keep the vol pot to DCB1 wiring short.

It's the input wiring and the output wiring that can be (much) longer.

 

[ghiglie]

It works.

remember to keep the vol pot to DCB1 wiring short.

It's the input wiring and the output wiring that can be (much) longer.

I'll keep note of this too. Thanks!



Inviato dal mio ZP998 utilizzando Tapatalk

 

[mbain]

I went to buy an AC inlet yesterday and ran into a barrage of unexpected choices. Termination type, filtered or unfiltered, fused or unfused, switched or unswitched, amperage rating etc. Will someone please tell me which type to purchase?

 

[Salas]

Fused and possibly switched. Filtered not necessary in this one unless you live in a particularly dirty mains area.

 

[AndrewT]

I would have said filtered was the main criteria.
The current rating to suit the load (transformer rating).

Switch and fuse can be added separately, filtering is not as effective if added separately.

 

[BigE]

7-10V DCin-DCout for the regs is OK. There is no problem with maxDCin other than heat.

Thank you!

I have massive heat sinks ( 2 pieces 10" x 4" x 1") which makes me think that +14 VDC in should not really matter....

I guess it could be worth a shot! At least on the test bench, where I can monitor the heat being produced. I can borrow a remote temperature sensing gun for the event.

I suppose that inserting a resistance in series with L is not a good idea? or maybe CLCRC to reduce the voltage?

 

[AndrewT]

If your current draw is constant, then an added resistor will drop a constant voltage.
That is a good way to move some of the dissipation from the semiconductors to fixed Power Resistors.

The CCS in the DCB1 ensures that the current draw is constant. Therefore use a resistor with appropriate dissipation capability related to value selected.

 

[Erlend Sæterdal]

It works.

remember to keep the vol pot to DCB1 wiring short.

Why is that so important ?

 

[AndrewT]

The high output impedance of the vol pot is unable to source the current that longer interconnects will demand.

 

[Erlend Sæterdal]

The high output impedance of the vol pot is unable to source the current that longer interconnects will demand.

Depends on how cables are made as well right ? I use 0,4 mm twisted pair 15 cm aprox.

 

[BigE]

If your current draw is constant, then an added resistor will drop a constant voltage.
That is a good way to move some of the dissipation from the semiconductors to fixed Power Resistors.

The CCS in the DCB1 ensures that the current draw is constant. Therefore use a resistor with appropriate dissipation capability related to value selected.

Thanks AndrewT!

If I follow, here is an example: For 600 ma per device, a total current of 2.4 A is flowing. Given R=V/I to drop 3.6 volts would take a 1.5 ohm resistor.

Since P=IV, the dissipation is near 5.4 watts. A 20 watt resistor on each polarity would be very reliable.

I do have some questions though...

Can the 20 watt resistor be attached directly to the secondary? ie Transformer secondary -> Resistor -> Diodes -> Cap bank? Or is CRC preferred? (I think it does not matter where)

What is recommended max dissipation for the 20 watt Resistor? ( Is it 1/3rd of the rating? )

Thanks again!

 

[bullmout]

Hello
I finish to populate m'y dcb1 black édition . And i have a problem , i have no sound to output , i have no click on Relay . When îpowered the board , i have 12v on the first Relay pin but no clik .
I m not an electronic superman , if you have a way for m'y problem .
Thanks

 

[Salas]

Check that the BC550 and BCB17 in the relay circuit are OK.

 

[bullmout]

can you tell me how to control them. when I touch their center pin ,relay click is on panic .and juste touch!!! any connection , My relay is haunted ..

 

[Salas]

The relay is 12V type non latching, you put a jumper where it has "NOTE" printed, and you got both types BC550 and BC517 I presume. No substitutes or BC550 for both. In that case put a new BC550 in place of the old first.

 

[bullmout]

i have the jumper "note" and bc550 and bc517 .
i go to buy a new bc550 and test it .

 

[AndrewT]

Thanks AndrewT!

If I follow, here is an example: For 600 ma per device, a total current of 2.4 A is flowing. Given R=V/I to drop 3.6 volts would take a 1.5 ohm resistor.

Since P=IV, the dissipation is near 5.4 watts. A 20 watt resistor on each polarity would be very reliable.

I do have some questions though...

Can the 20 watt resistor be attached directly to the secondary? ie Transformer secondary -> Resistor -> Diodes -> Cap bank? Or is CRC preferred? (I think it does not matter where)

What is recommended max dissipation for the 20 watt Resistor? ( Is it 1/3rd of the rating? )

Thanks again!

Put the added R between two sets of C, i.e. rCRC
The first rC Filters some of the HF.
The second RC filters a lot more of the HF and some of the MF.
The combination rCRC manages to filter most of the 100/120Hz from the mains fundamental after rectification.

I would suggest that no resistor have a continuous dissipation exceeding 50% of maximum at that Ta. Inside a hot chassis that could be <30% to 40% of the cold maximum rating.

How did you arrive at 2.4A from 600mA? (not 600ma)

 

[bullmout]

hello .

im a stupid boy !!!! i inverse polarity on little caps , who works whith c550 and c517 ..
and now relay click !!

 

[Salas]

hello .

im a stupid boy !!!! i inverse polarity on little caps , who works whith c550 and c517 ..
and now relay click !!

The Devil is always in the details, isn't he?

 

[bullmout]

Yes

You think i must change the caps , about work with bad polarity ?