need to drive dual supply op amp with 12Vdc battery supply - Page 1
Forum section: electronics / beginners

author: NASK
author_rank: Contributor
timestamp: July 09, 2018, 05:52:14 am
content: HiI need to drive dual supply op amp with 12Vdc battery supply. Therefor wish to follow this circuit. It makes +/- 6V with virtual ground.Q1. Is it suitable to drive opamp or other recommended methods?Q2. If I want to get +/- 8V from 12Vdc battery supply; what are the changers need to do? (I try with two op ams and changing divider resistor value to 20k and connecting two op amp virtual terminals together but didn’t work)

author: Rbastler
author_rank: Frequent Contributor
timestamp: July 09, 2018, 07:50:09 am
content: Quote from: NASK on July 09, 2018, 05:52:14 amIn this case I would use a ICL7660A. Its important you get the A version, since the non A version works only up to 10V, but the A version works to 12V.

author: Zero999
author_rank: Super Contributor
timestamp: July 09, 2018, 08:01:00 am
content: What's the purpose of the circuit?It might be possible to avoid a bipolar power supply.

author: David Hess
author_rank: Super Contributor
timestamp: July 09, 2018, 04:05:10 pm
content: Quote from: NASK on July 09, 2018, 05:52:14 amYes but lower the value of R1 to like 10 ohms and put 100 microfarad aluminum electrolytic capacitors between the output and each supply line to reduce the AC impedance.QuoteTwo operational amplifiers will not work for this but a ICL7660A charge pump like Rbastler suggests would. Or for a little more grunt, an LTC1144.

author: Relayer
author_rank: Contributor
timestamp: July 10, 2018, 12:21:06 am
content: Hello NASK,In your pictures, you mistakenly have ground in the incorrect spot.Please refer to picture below:I hope the above helps.Regards,Relayer

author: NASK
author_rank: Contributor
timestamp: July 12, 2018, 02:54:59 am
content: thank you all for reply, this requirement is sine wave & triangle wave generator design using op-amp.hi Relayer,your given picture virtual ground is connected with real ground i think it is not essential because it just connecting to chassis.

author: Zero999
author_rank: Super Contributor
timestamp: July 12, 2018, 07:53:54 am
content: Quote from: NASK on July 12, 2018, 02:54:59 amThen there is no need for a dual supply. It can easily be implemented using a single supply.

author: NASK
author_rank: Contributor
timestamp: July 13, 2018, 02:41:26 am
content: hi Hero999, Here I have attached my circuit for sine wave generator and its out put , please could you tell me how design it ? ( highly appreciated if you could explain with theory, thanks)

author: Psi
author_rank: Super Contributor
timestamp: July 13, 2018, 06:22:05 am
content: If you do need a split supply I would just throw an $8 DCDC module at the problem.One that will give you a. +/- output.Or it might be better with a single isolated output dcdc just to generate the negative.Of cause you do need to consider battery lifespan. Any solution other than two batteries is going to use some powerFor the conversion, even when your not powering anything

author: Zero999
author_rank: Super Contributor
timestamp: July 13, 2018, 10:37:20 am
content: One problem with those DC:DC converters is they can be noisy, so might need some additional filtering.Quote from: NASK on July 13, 2018, 02:41:26 amUse the spare op-amp in the LM324 package to generate another power rail, at half the supply voltage and use that for all the 0V DC nodes in the original circuit. The 0V AC nodes and outputs can be connected to the new 0V connection, via capacitors.I've implemented the electrical modifications to the circuit, but you need to redraw it to make it easer to follow. The circuit is very poorly drawn and is very confusing. Flip the op-amps and use labels for the power supply connections to get rid of most of the wire crossings.

author: Old Printer
author_rank: Frequent Contributor
timestamp: July 13, 2018, 04:21:32 pm
content: Very good video on powering Op Amps by W2aew (Alan Wolke).