MPP

FdW · 2011-12-20 3:13 pm

LED's do the LED's it's x'mas (even though it may not be the cheapest) Maybe 2 green and 2 red one's (again it's x'mas)

Joachim Gerhard · 2011-12-20 3:15 pm

Here is the my little circuit.
What is also good with Leds is that they show that a particular part of the circuit is under current.

Joachim Gerhard · 2011-12-20 3:40 pm

We can make space for 4 Leds in series, then we can use cheeper colours if we like.

Benedetto · 2011-12-20 4:40 pm

Imho,
nowadays the price for blue Leds is no longer an issue.

RCruz · 2011-12-20 5:19 pm

Cool. I like leds and this way we avoid zener noise in the opamp psu but I would avoid blue ones.

I experimented a lot with leds on series regs and the lower noise ones are yellow / orange. mine have 1.9Vdrop at 20mA so I will use four for each rail.

MiiB · 2011-12-20 5:37 pm

Here's the updated circuit, with LED reduced supply for the Op-amp..

Joachim Gerhard · 2011-12-20 5:52 pm

Thanks Michael. We come close.

hesener · 2011-12-20 7:36 pm

LED reduced supply captured in the schematic. now to the shunt regs....

MiiB · 2011-12-20 7:47 pm

Lots of work makisng pcb's....

hesener · 2011-12-20 8:31 pm

you bet.....

here are the schematics of the preamp and regulators, please take a look if everything is correctly captured. I will start floorplanning with these versions now. I believe the consensus was that the transformer, rectifier and bulk caps are supposed to be in an external enclosure, correct?

enjoy.....

Joachim Gerhard · 2011-12-20 8:55 pm

Yes, i call that the pre regulator. That belongs in a separate box.

FdW · 2011-12-20 8:55 pm

hesener said:
you bet.....

here are the schematics of the preamp and regulators, please take a look if everything is correctly captured. I will start floorplanning with these versions now. I believe the consensus was that the transformer, rectifier and bulk caps are supposed to be in an external enclosure, correct?

enjoy.....

In the power supply

R105/205 originaly 500 Ohm kan be 470 Ohm

R106/206 should be 2K or 2K5 trimmers to adjust the output voltage

Otherwise it seems o.k.

Regards,
Frans.

FdW · 2011-12-20 8:58 pm

hesener said:
you bet.....

here are the schematics of the preamp and regulators, please take a look if everything is correctly captured. I will start floorplanning with these versions now. I believe the consensus was that the transformer, rectifier and bulk caps are supposed to be in an external enclosure, correct?

enjoy.....

Also change the BC550/560 to BC327/337, that is more in line with preamp. Just for fun

Joachim Gerhard · 2011-12-20 9:05 pm

On first sight the schematics look right.
I will print them out and look more careful later.
Please make space for 4 Leds in series before the servo, just in case somebody is not comfortable with the blue Leds. For some servo ICs we have to drop to plus-minus 15V.
For example the AD825 can stand only plus-minus 15V. Some say it has magical properties as a servo because it has an open loop bandwidth of 10kHz. With 12nV/qHz it is a bit noisy though but that does not play a big role here.

Joachim Gerhard · 2011-12-20 9:06 pm

Yes, the same transistors everywhere. That is really unique.

Joachim Gerhard · 2011-12-20 9:08 pm

http://www.analog.com/static/imported-files/data_sheets/AD825.pdf

hesener · 2011-12-20 9:11 pm

transistors changed to BC327/337, resistors to 470, two trimmers with 2k/10turns, LEDs added

at this point it looks like the 100x160mm PCB might be a little too small.... we'll see....

MiiB · 2011-12-20 10:12 pm

It's camped....You'll really need to make i tight...

RCruz · 2011-12-20 11:28 pm

Swifter than a Cadilacc glide...

Joachim Gerhard · 2011-12-20 11:30 pm

Red and silver is correct.

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