+24Vdc from +/-15Vdc

[Svart]

I'm not sure why anyone would use anything but a nice handy FET here..  Simple Nchannel and a 10k resistor is all that's needed.  I have a couple out there in the world with this and they've worked for years. 

 

[peter purpose]

Simple Nchannel and a 10k resistor is all that's needed. 

Stick them in a bit of blu-tack and throw them at the cat?

 

[peter purpose]

Is this the kind of thing to turn the old girl on at leisure?

With that cap to ground instead of to the emitter of Q1 it'll be more of a rude awakening (assuming the cap's empty at turn-on). Also if V1/V2 drop rapidly at turn-off Q1 BE might zener.

Otherwise... maybe. The TDK data sheet doesn't give enough information here (other than that the RC pin may source up to 1mA). The slew rate on the collector of Q1 looks awfully slow, and the CC6 may well not like that. Best case it might work, worst case it could go boom (literally).

A single OC-out comparator with some hysteresis is a safer (but more expensive) bet.

JDB.

Thanks JD.

 

[Svart]

Stick them in a bit of blu-tack and throw them at the cat?

I'm not completely up to speed on my cockney..  translate please.

;D

 

[peter purpose]

I'm not completely up to speed on my cockney..  translate please.

;D Roughly translated as......

Am I on the right track Dan?

 

[peter purpose]

I also used a simple transistor turn-on circuit that keeps the converter off until the rack is near full supply, or it's initial surge will cause the regulators of the rack to current limit.

Guys... I'd really like to get this right. I could experiment like a mental bastard, or someone could kindly point me in the right direction.

Grassy arse.
peter

 

[onlymeeee]

Alright Peter,

I went with a single transistor operating as a constant current source.

Haven't got circuit on this puter but it's an adaptation of the left circuit

Dunno if that helps or confuses matters.

I've tried it and it works.  I haven't however tried 11 in a rack or whatever yet.

Guess it's up for debate to which is the better approach.  I'm not taking sides, which ever one wins I'll be doing from now on! Fickle like that

 

[peter purpose]

Dunno if that helps or confuses matters.

??? Where's the booze?

I'll have a play.. cheers

 

[onlymeeee]

Dunno if that helps or confuses matters.

??? Where's the booze?

Oh, it's close by

 

[Svart]

I'm not completely up to speed on my cockney..  translate please.

;D Roughly translated as......

Am I on the right track Dan?

I meant shunting the 10k from the gate to -15V.  This is to pull the gate down when you don't have a high gate signal.  You can get conditions where the charge will couple over the passivation in the FET to turn itself on.  Unless of course your are actively driving the gate high and low.  I generally put a gate pull-down resistor anyway just in case.

 

[djn111]

Hi,

Why not using a of the shelf solution like this one VLA106-15242

DJN

 

[onlymeeee]

Hi,

Why not using a of the shelf solution like this one VLA106-15242

DJN

Not quite enough power with that one

 

[peter purpose]

A simple transistor turn-on circuit being the operative phrase.

 

[peter purpose]

scrub

 

[djn111]

Hi,

I believe the VLA106-15242 can deliver 100mA, 24VDC, so with the current inrush limited to 90mA it should be oke.

DJN

 

[onlymeeee]

Hi,

I believe the VLA106-15242 can deliver 100mA, 24VDC, so with the current inrush limited to 90mA it should be oke.

DJN

What are we saying the module needs?  106mA ±10mA at 24V DC ?

Peter, was that 'scrub' circuit in ref to the one I'm using?
If so, I'm not using the RC pin to switch.
I'm using transistor as a constant current source.
Maybe I've got a small pcb somewhere you can have to have a 'play' with?
Or maybe a fully built one as a trade for one of those lovely red marconi knobs?

 

[peter purpose]

What are we saying the module needs?   106mA ±10mA at 24V DC ?

Peter, was that 'scrub' circuit in ref to the one I'm using?
If so, I'm not using the RC pin to switch.
I'm using transistor as a constant current source.
Maybe I've got a small pcb somewhere you can have to have a 'play' with?
Or maybe a fully built one as a trade for one of those lovely red marconi knobs?

Around that figure, but I always want plenty more on tap should the big waves roll in.
The 'scrub' was me doodling, with a glaring mistake.
I will be using the CC6.. and the RC pin... and as I've just bought a couple.. and can afford to destroy one in the name of experimentation.... I'll fiddle and fudge my way there eventually.

Keep your pcb... One Red Marconi bar knob has your name on it.

 

[onlymeeee]

Yeh CC6 works well.  One input cap and one output cap and I have no noise problems. Looks straight on the scope.
Yeh I bought 4 to destroy 3 but all survived... Well, I think the first one over no-mans-land is wounded, but should recover when called up again.

I suspect the ultimate circuit would be a combination of both mine and a slow-start-on circuit too.

Only because it is a double wide module, I wonder would it be fine with inrush current if you could fit twice as many in a lunchbox? (All be it, without all the LEDs) 

Anyone know how Avedis does it?  Though even they state there could be an issue with inrush current.

a knob with my name on it! Normally it's the otherway round! (the name 'knob' on me!) Cool!

 

[peter purpose]

;D

Draw the bleedin thing out then....!!

 

[peter purpose]

Power delay sorted. Thanks Dan.