Easy Method of switching 3vdc

[cromerro]

Hi -
I have +3VDC and -3VDC input from a carbon battery bank. I want to be able to have a single output pin
whereby I can output first battery +3VDC for 12 minutes and then switch the output pin to battery -3VDC for
the next 12 minutes, repeating on a forever basis. The 3v output simply attaches to a screen providing a weak field.

Is there any real simple way of using the GPIO ports on the Rpi and a simple looping program to accomplish
this task? I have an early Rpi that I could use for this.
Thanks,
Bob Cromer

[FLYFISH TECHNOLOGIES]

Hi Bob,

I have +3VDC and -3VDC input from a carbon battery bank.

Input from battery bank ?
Is your battery bank 3V and has two output terminals: + and - ?

In order to understand what you'd like to achieve, we (including you) need to analyze components and specify goals properly.
Feel also free to draw a sketch...


Best wishes, Ivan Zilic.

[Ravenous]

The 3v output simply attaches to a screen providing a weak field.

Am I right in guessing you first want to apply +3V, then -3V, and you have four 1.5V cells with the earth in the middle?

If this is being run indoors with other power available - so the apparatus itself is mainly powered from mains, not the batteries themselves - I would just buy or build a relay board and use two relays to connect either the positive or negative end to your electrode/screen.

I'm suggesting relays because their outputs are physical switches insulated from the rest of the circuit, so only your 3V battery is connected to the electrodes.

There have been a few posts on how to switch relays on and off, so if what I've describes is what you need then you could just have a search around and see what's available.

[BMS Doug]

The 3v output simply attaches to a screen providing a weak field.

Am I right in guessing you first want to apply +3V, then -3V, and you have four 1.5V cells with the earth in the middle?

If this is being run indoors with other power available - so the apparatus itself is mainly powered from mains, not the batteries themselves - I would just buy or build a relay board and use two relays to connect either the positive or negative end to your electrode/screen.

I'm suggesting relays because their outputs are physical switches insulated from the rest of the circuit, so only your 3V battery is connected to the electrodes.

There have been a few posts on how to switch relays on and off, so if what I've describes is what you need then you could just have a search around and see what's available.

+1
use a GPIO to switch relays to switch your power supply.
Caution: use care that the relays cannot accidently short out your battery bank if the switching condition isn't what you would expect.

is it essential that the output voltage remains constantly powered?
if so you may need to use capacitors to cover the switching time.

[danjperron]

You only need one GPIO.

Just one relay will do.

N.O. to +3V
N.C. to -3V
The flipper to the screen.

there is a lot of relay available which could run on 3.3V. Check some Arduino shield.

Daniel