One way power supply

Thread Starter


Joined Jan 13, 2010
Hello Readers,

Here is a very basic query about power supply in electronics.

If suppose i have three different LED lighting circuits (all three circuits are 555 based), all three circuits require a power supply (PS) of 12volt DC (1amp), i just have one 12volt (8amp) battery and I would like to power all three lighting circuits with this single 12volt battery. Powering all the three circuits parallely with one 12 volt battery doesn't seem to be working, the lighting circuits work but with abnormal behavior, the circuit doesn't lit up the LEDs as it is designed to do, If i am not mistaken it seems it is because of the reverse current.

So, What shall i do, i mean how do i create a ONE WAY POWER SUPPLY for each circuit? Do i need to add some component at the PS input of each circuit to avoid reverse current, so that all three circuits can work properly even by sharing the same PS.

Any wise advises & recommendations will be deeply appreciated.
Thank You.

Best Regards.
Last edited:


Joined Feb 19, 2009
Are you trying to wire them in series?

Hook the + of the battery to the - of each board, one at a time to make sure that board works.

Once you verify all 3 boards work, tie the + of the battery to the + of all 3 boards, and the - of the battery to the - of all three boards.


Joined Dec 26, 2010
You may have the problem described here in post #3:

If all circuits work iwhen connected to the power supply individually and start showing strange behaviour when connected together you may need to decouple the circuits.
Yes, that could very well be so. The standard 555 timer IC is particularly well known for drawing transient currents from its power supply, and its operation can be affected if the power supply voltage is not steady.

This is explained in the thread you referenced, but it may be worth noting that this is a particular example of the general need for supply de-coupling. I didn't see if the 555 thread mentions it, but there is also a "sticky" thread on decoupling generally. It's worth a read: