Hello,
I'm using two batteries (actually 2 sets of 2 AA's) to get a +3V, -3V and virtual ground. They are in the configuration shown in the attached image. I have a few beginner's questions about this setup, could you help me think through them?
If I had one battery, I'd know that if either terminal wasn't connected, the circuit would be open with no power flowing and therefore no drain on the battery. But what happens with my two sets of batteries and three wires?
If I disconnect the +3V wire, I would imagine there would still be a drain on the lower battery, and the outputs would change to +3V and -3V (where they were virtual ground and -3V). Likewise if I disconnect the -3V wire, I expect +3V and -3V would now come off the top battery. I'm assuming here that the rest of the circuit connected to the wires will drain a current if it can. If I disconnect the virtual ground, I assume that the top and bottom wires now give +3V and -3V.
Unless I've got anything wrong there (please say!), this leads to my first question: how do you switch the power off with a setup like this? My reasoning is that it requires a two way switch that disconnects both the virtual ground and another terminal. I'm reaching this conclusion because if you disconnect the one terminal, there's a current across the other two, and if you disconnect the 3V and -3V without disconnecting the virtual ground, you have a + and - terminal connected, which although they are on different batteries could make them discharge each other.
Is this right, and as importantly, am I thinking about this correctly? I'd be grateful for your comments as I'm keen to understand this properly.
Secondly, I see circuits that use a few capacitors and sometimes diodes around the virtual ground. What are they for? My best guess is that they aim to keep the vg at 0V and counteract the effects of either battery discharging quicker than the other. Is that correct? How should such a circuit be set up, which what values for the caps and when does it need diodes?
Finally, is it possible to get a virtual ground with a single battery? I tried doing this with a 9V PP3, running wires off the +4.5V, -4.5V and another wire connected to both, shown in the second picture. This didn't work at all - the battery got hot quickly and I disconnected it, I guess I was short circuiting it. Is it possible to get a virtual ground of a single battery?
Thanks,
Ogg
I'm using two batteries (actually 2 sets of 2 AA's) to get a +3V, -3V and virtual ground. They are in the configuration shown in the attached image. I have a few beginner's questions about this setup, could you help me think through them?
If I had one battery, I'd know that if either terminal wasn't connected, the circuit would be open with no power flowing and therefore no drain on the battery. But what happens with my two sets of batteries and three wires?
If I disconnect the +3V wire, I would imagine there would still be a drain on the lower battery, and the outputs would change to +3V and -3V (where they were virtual ground and -3V). Likewise if I disconnect the -3V wire, I expect +3V and -3V would now come off the top battery. I'm assuming here that the rest of the circuit connected to the wires will drain a current if it can. If I disconnect the virtual ground, I assume that the top and bottom wires now give +3V and -3V.
Unless I've got anything wrong there (please say!), this leads to my first question: how do you switch the power off with a setup like this? My reasoning is that it requires a two way switch that disconnects both the virtual ground and another terminal. I'm reaching this conclusion because if you disconnect the one terminal, there's a current across the other two, and if you disconnect the 3V and -3V without disconnecting the virtual ground, you have a + and - terminal connected, which although they are on different batteries could make them discharge each other.
Is this right, and as importantly, am I thinking about this correctly? I'd be grateful for your comments as I'm keen to understand this properly.
Secondly, I see circuits that use a few capacitors and sometimes diodes around the virtual ground. What are they for? My best guess is that they aim to keep the vg at 0V and counteract the effects of either battery discharging quicker than the other. Is that correct? How should such a circuit be set up, which what values for the caps and when does it need diodes?
Finally, is it possible to get a virtual ground with a single battery? I tried doing this with a 9V PP3, running wires off the +4.5V, -4.5V and another wire connected to both, shown in the second picture. This didn't work at all - the battery got hot quickly and I disconnected it, I guess I was short circuiting it. Is it possible to get a virtual ground of a single battery?
Thanks,
Ogg
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