Have a projct for a timer

[sourcy52]

Hello,

Would like some feedback on the following.

Need: timer for alternating current of a 3-4.5 volt source. needs to switch from pos - to neg -to pos etc. every 15 minutes.

thanks for any pointers as to where to look for info - or help.

daniel

 

[InventionUnlimited]

3 to 4.5 volts AC cycling every 15 minutes, or a DC polarity reversal every 15 mins? I am thinking that you are reffering to the latter in which case a 555 (depending on accuracy required) and a DPDT relay to do the polarity reversal. Can you give any additional infor to help us understand your needs.

 

[sourcy52]

You are correct, it would be a polarity reversal every 15 min. And I was told it would need a 555 timer somehow.

It would be a 9 d-cell setup for the source of energy

 

[InventionUnlimited]

sorry its really rough, im on the wifes PC, so no schematic capture progs here. hope this helps


oops, sorry this is alternating the 13.5 volts, your relay would be connected to the 3 to 4.5v supply rather than the 13.5 other than that its exactly the same. Can you tap the 3rd cell in the battery pack for your 4.5v or is it a sealed unit?

 

[sourcy52]

wow, thanks, really didn't expect the response so quickly.

only problem is I have no idea what your drawing means. will copy and show to someone who might.

thanks, again!!

daniel

 

[blueroomelectronics]

A little 9V battery won't last long. That relay will drain it quickly.

 

[InventionUnlimited]

Its not a 9v battery, its 9 x 1.5v 'D' batteries, the ones used in the security style MAG Lite. **broken link removed**