Hi.
I'm building 4 drivers for 4 VU meters according to the famous "modified ESP P87A balanced driver" circuit based on a TL072 dual op amp (approx. 4x 3mA power consumption). I also want to illuminate those VU meters using 4 white LED (approx. 4x 20mA power consumption). I already have my PSU with +/-15VDC. I'm using a 24-0-24VAC (9W) transformer for that.
I have 2 options:
1st: to use just one side of the transformer secondary 24V-0V and run +/-15VDC from there with a virtual ground and use the other 0V-24V just for the 4 LEDs. This way the voltage regulators on my PSU won't heat up.
2nd: to use the whole transformer with center tap and connect the LEDs to each VU driver (works with a 5k1 resistor). Using this configuration, my PSU would turn 24VAC into almost 34VDC and then regulate them down to 15VDC, thereby wasting some power by creating heat...
Another question is whether to connect these LED in series or parallel and the respective resistor?
So, what would be the best way to power 4 drivers and 4 LED.
What would the gurus suggest?
Phantombox
I'm building 4 drivers for 4 VU meters according to the famous "modified ESP P87A balanced driver" circuit based on a TL072 dual op amp (approx. 4x 3mA power consumption). I also want to illuminate those VU meters using 4 white LED (approx. 4x 20mA power consumption). I already have my PSU with +/-15VDC. I'm using a 24-0-24VAC (9W) transformer for that.
I have 2 options:
1st: to use just one side of the transformer secondary 24V-0V and run +/-15VDC from there with a virtual ground and use the other 0V-24V just for the 4 LEDs. This way the voltage regulators on my PSU won't heat up.
2nd: to use the whole transformer with center tap and connect the LEDs to each VU driver (works with a 5k1 resistor). Using this configuration, my PSU would turn 24VAC into almost 34VDC and then regulate them down to 15VDC, thereby wasting some power by creating heat...
Another question is whether to connect these LED in series or parallel and the respective resistor?
So, what would be the best way to power 4 drivers and 4 LED.
What would the gurus suggest?
Phantombox
Personally, I would avoid virtual ground, given the choice. Make sure the DC voltage of your power supply does not exceed the max. input rating of your regulators and allow for space for heatsinks.
I would put the LEDs in parallel with individual resistors in series to provide 10 mA each. E
I would put the LEDs in parallel with individual resistors in series to provide 10 mA each. E
- Status
- Not open for further replies.