Hi Gentlemen,
Perhaps you can assist with a recommendation for changing the Negative
output of the LM723CH in power supply circuit for a Bruel & Kjaer 2609
Measurement Amplifier.. Schematic attached.
I started the calibration and adjustment procedure
The negative rail is at -17.126 and it needs to be boosted to
the -18V. The exact specification of V20 Pin 5 is -17.7 to18.5 Volts.
There is barely enough room to change a resistor. It's a very tight
fit. Otherwise I would place a pot in it in the voltage divider with
the feed to the Inverting input. I could calculate it a resistor value but
I don't how how the LM 723CH responds to changes in Inverting voltage
changes if at all. I'd rather not have to pull and replace parts more than
necessary it if VERY tight right there.
I thought about doing it on the trace side of the board but there is no clearance
when the bottom is slid back on.
I've looked at the data sheet from TI and it doesn't help as their circuit
designs are different. Also puzzling on the schematic (Fig 18, Page 9) shows one extra pin for the 10 pin device 11 pins?
Here's the TI Link. LM723CH (rev C)
Any Ideas, suggestions?
Cheers,
Sync
Perhaps you can assist with a recommendation for changing the Negative
output of the LM723CH in power supply circuit for a Bruel & Kjaer 2609
Measurement Amplifier.. Schematic attached.
I started the calibration and adjustment procedure
The negative rail is at -17.126 and it needs to be boosted to
the -18V. The exact specification of V20 Pin 5 is -17.7 to18.5 Volts.
There is barely enough room to change a resistor. It's a very tight
fit. Otherwise I would place a pot in it in the voltage divider with
the feed to the Inverting input. I could calculate it a resistor value but
I don't how how the LM 723CH responds to changes in Inverting voltage
changes if at all. I'd rather not have to pull and replace parts more than
necessary it if VERY tight right there.
I thought about doing it on the trace side of the board but there is no clearance
when the bottom is slid back on.
I've looked at the data sheet from TI and it doesn't help as their circuit
designs are different. Also puzzling on the schematic (Fig 18, Page 9) shows one extra pin for the 10 pin device 11 pins?
Here's the TI Link. LM723CH (rev C)
Any Ideas, suggestions?
Cheers,
Sync