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Really Basic Power On Question

Started by Bret Cahill February 16, 2021
This must be a really really common problem and the only reason it is diffi=
cult to find on youtube is the wrong search terms:


If a device has a power on button latch switch and you want it to turn on a=
nd off like a light bulb, i. e., when the power supply is plugged in or a r=
elay connects the power, or for solar, when the sun comes up, is it a commo=
n solution to run a wire from the power supply through a cap and maybe a la=
rge drain resister in parallel then to one side of the latch switch?

The current would flow through the cap just long enough to set the latch sw=
itch before the cap is charged and stops the flow.

Then the device turns on and stays on until power is disconnected.  The pro=
cess can repeat after the charge drains off the cap.

First check the voltage through the on switch is the same as the power supp=
ly.  (This will not werk on a lap top.)

I'd need some idea of the time it takes to latch and some thresh hold volta=
ge for the latch to select the cap and resister.  Maybe look at it on an os=
cilloscope.

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Bret Cahill wrote:
> This must be a really really common problem and the only reason it is > difficult to find on youtube is the wrong search terms: > > > If a device has a power on button latch switch and you want it to turn > on and off like a light bulb, i. e., when the power supply is plugged > in or a relay connects the power, or for solar, when the sun comes up, > is it a common solution to run a wire from the power supply through a > cap and maybe a large drain resister in parallel then to one side of > the latch switch?
don't follow your description here at all. Are you just trying to figure out a "simple" way to pulse a latching relay's coil long enough for it to set? Note that in order to reset a latching relay, one normally needs to drive a secondary coil, or reverse the current flow in a single coil model; so if I'm understanding your question properly, you're never actually going to "unlatch" the relay. -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEE3asj+xn6fYUcweBnbWVw5UznKGAFAmAvtB4ACgkQbWVw5Uzn KGBrSxAAoFvVmlRMMMicwRGAnjAtX/oQRumYcTUUq4XsDcWG1mLRQExYBcR2PiO+ VYjYgxZESLmobjSdoVn02MLCvW2qBmtDyLAR9+c0hR9dycT8O4XH48rfKFVm2lKA leJq0DZKJyCqQd0mtAZNT5OOo9BVqIqIEVZhe/ZD8BeoRqtx6oAk6lk9/Yzd9Z2Y JW3wriI0cSZ1JiJ7yo5eHdCp32jug693BwhFvcVeL+4ltrt8yhLM3fPdqjd1HoUx mOWO+hNpkZWYtZRkImfvSswXNts/i3k4cg/DLaZmaSqBaHI8TfgEk/+zi1N8Dbjy fwOj0bvdVnJyizI0Y4KN6ahzpvo4A0FUq5IGelzFvyJopM1HE+fy7xr3uN/0FNrq f9oqblW8cDv5fDeGO+wn9GJtepdqxM4eLfa/SJOZ/ggLxeDhGR5v9DxWvgfOqjXY igQuuotbibW92YsYwNcOgaI/+LPtmZCTkj8mNtvz/CCpoH/fJ1T7FJON+EZ/+Pg4 JTkhSkG4VpQfejsGBD8dHGqV2kfxWOvMp3EPrEXKr2biNFTlQghbOdTDgqRCFL1j CTWsuaZgdUB2phY+sGP+f+mQSEe8vXNH0qY/Zta0i2wF2jiUdAwaWVZ0I2ViMbe0 rRSfO/CklETGrd1h52N3qG6uozrj48rsU66JwjMFOb4et7u2+ZA= =CM+M -----END PGP SIGNATURE----- -- |_|O|_| Github: https://github.com/dpurgert |_|_|O| PGP: DDAB 23FB 19FA 7D85 1CC1 E067 6D65 70E5 4CE7 2860 |O|O|O| Former PGP: 05CA 9A50 3F2E 1335 4DC5 4AEE 8E11 DDF3 1279 A281