Reflektor-D builds

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#545
12VDC output yes if you scale up the Vref and use external sinks. Like using an LM329 and two greens for setting the voltage. Also 15VAC transformer. On board sinks would still suffice when not setting above 250mA CCS (2.4 Ohm R1).
 
#546
Salas,

I would like to use two boards for +/-5v application.
Is it OK to use one secondary and one bridge rectifier like attachment below?
(DC in configuation and keep CM and Cd)
 

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#549
I hope that you will find Ref-D as nice on DAC too. Let us know. Stacking two positives to make a symmetric needs separate isolated primaries, but using other transformers for digital and analog is good anyway.
 
#550
if you have dual secondaries and dual rectifier to create two isolated supplies then you can use either +ve or -ve regulators on either of both of the isolated channels.
Then combine them later to create a dual polarity or multi voltage supply.

If you have a centre tapped transformer (or dual converted to centre tapped) and a single rectifier then you must use a +ve and -ve regulator pair to create a dual polarity supply.
 
#552
ODD problem, need help!

Hi,
So, I'm using Tea-bags reflector boards and parts to power the 5v5 for the Twisted Pairs Buffalo Sabre II DAC board.

When I connect it up the voltage shows 4v85, and only about half of the LEDS on the Trident Regs, mouted on the DAC, light up?

Checked the current draw of the DAC by running the B+v in series through my meter and got a 406mA reading, which it should be. Then noticed that the LEDS were all on? Also, the voltage read 5v5, which it also should be.

Powered up again with out the meter and got 4v85 and some LEDS not on again!!??

Did this back and forth several times! I'm stumped. 😕
 
#559
Salas said:
Just make sure there are no max demand situations in the circuits that may challenge the 0.25A current limit
Click to expand...

0.25 is more than enough.

I'm thinking to use another Reflektor-D to supply 5VDC to ARM SoC mini computer BeagleBone Black (BBB) as a music player. I measured the current and it turns out that with wifi dongle plugged in and 50% CPU usage (with upsampling switched on to max 192kHz) BBB consumes approximately 400mA. I also want to use 3.7V 500mAh liion Rechargeable Battery with BBB.
And don't know what value of R1 resistor should I select for BBB with mentioned battery.

BBB uses as Power management chip the TPS65217C 'Single-Chip PMIC for Battery-Powered Systems'
On 25 page of the datasheet I can find:
Charging current is automatically reduced when system load increases and if the system load exceeds the maximum current of the USB or AC adapter supply, the battery will supplement, meaning that the battery will be discharged to supply the remaining current.
Click to expand...
I measured the current draw during player (BBB) switched on and simultaneous charging the completely discharged battery. It was 900mA at the beginning and within an hour, the current decreased to 400mA. It will be rare situation to start with completely discharged battery.
Can I assume than with R1=1ohm for max 600mA and normally BBB current draw=400mA remaining current 200mA would be used to charging the battery? What do you think?
What R1 value would you suggest for Reflektor-D + BBB and the battery?
Regards,
bern
 
#560
Can't assume, you should check with your 1 Ohm in practice I would think. And then increase the current only if not sufficient. Its only a current limiter after all, if there will be more demand it will just cut out the client circuit from what it tries to do, it won't overpower it. Iccs=0.6V/R1
 
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