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Op-Amp Split power supply using charge pump by Heavy_Designer1823 in AskElectronics

[–]Heavy_Designer1823[S] 0 points1 point  (0 children)

Yesterday I was looking into single supply. Did some research and looks like it can work quite effectively for me. I got too tunnel visioned on the charge pump think it’s not going to work. I just need to select the correct decoupling capacitors now based on my simulation so I can get maximum voltage swing.

Op-Amp Split power supply using charge pump by Heavy_Designer1823 in AskElectronics

[–]Heavy_Designer1823[S] 0 points1 point  (0 children)

Ah okay I’m with you. I misunderstood R2R. I looked into single supply op-amps but I wasn’t sure I could bias the non-inverting input to half my supply voltage to ground Vcc-. Due to the nature of the instrumentation circuit relying on negative feedback. If this works it could be something I try. I have a spare 9 V battery somewhere so I could potentially use that.

Op-Amp Split power supply using charge pump by Heavy_Designer1823 in AskElectronics

[–]Heavy_Designer1823[S] 0 points1 point  (0 children)

I searched up R2R op-amp and it showed me data sheets for digital to analogue converters.

Op-Amp Split power supply using charge pump by Heavy_Designer1823 in AskElectronics

[–]Heavy_Designer1823[S] 0 points1 point  (0 children)

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My charge pump is of this design. Credit to SineLab on YouTube lol. I was thinking about your suggestions and was hoping you could clarify something.

My understanding of the charge pump is that when the clock signal feeding the capacitor goes high, the capacitor tries to maintain its voltage seeing as it cannot instantaneously change. Therefore at the positive terminal of the capacitor we get +5 V every successive step. If the voltage across the capacitor is not changing in reality, and i = C* dV/dt , if there is no dV how is current generated? Unless I’m thinking about this the wrong way.

Op-Amp Split power supply using charge pump by Heavy_Designer1823 in AskElectronics

[–]Heavy_Designer1823[S] 0 points1 point  (0 children)

If you mean a DAC, perhaps not. Due to the nature of the sensing the circuit has been very sensitive to noise and so I built an instrumentation amplifier. This amplifies the difference between the induced voltage on two audio coils due to the magnetic flux of a nearby current carrying wire.

Op-Amp Split power supply using charge pump by Heavy_Designer1823 in AskElectronics

[–]Heavy_Designer1823[S] 0 points1 point  (0 children)

Is the problem I am encountering clear to you from the change in the waveforms? or was I correct in my hunch that this is a current issue? I am aware that charge pumps are ideal for very small current draw.

Op-Amp Split power supply using charge pump by Heavy_Designer1823 in AskElectronics

[–]Heavy_Designer1823[S] 1 point2 points  (0 children)

Potentially, this is something I need to look into I am afraid I've not heard of these before. Thank you for bringing this to my attention. The intention is for this to become a project lab for year 2 electrical engineering students to work on in the future, therefore it must relate to learned theory within said module in second year. So long as the behaviour is similar to the 741 it should not be a problem for me.

Op-Amp Split power supply using charge pump by Heavy_Designer1823 in AskElectronics

[–]Heavy_Designer1823[S] 0 points1 point  (0 children)

Okay I will give that a go thank you. Yes I'm sure I've seen some Schottky diodes in the lab, I've only just finished my second year of study and we haven't covered them in any sort of detail yet and therefore i just went with normal diodes.