paralleling of solenoid cabinet locks?

Hi,

I'm really stumped on this one...

Can solenoids that are used to open door locks (house..) be wired in parallel, when multiple doors should be opened simultaneously?

The relevant part of the circuit is

For now, we have two doors to open simultaneously. The solenoid of the first has 200kOhm(!) DC resistance, the other 100ohm.

The solenoids work fine when individually connected to the above circuit's output header, but when both are connected to the header at the same time then only the 100ohm one latches. Which not only me thinks is quite odd... The +24V rail stays quite solid even when the 100ohm solenoid is engaged, and the mosfet's Vds then is just around 0.1V.

So, with my ignorance of the internals of solenoid door locks in general, is there perhaps some property there that makes wiring these things in parallel not possible?

thanks, - Jan

In my former workplace,all doors in the corridoors were held open with an electromagnet, at quiting time or fire alarm the power would go off,and all doors closed. So yes ,connect them in parallel,just supply enough power.

Dan Hollands kirjoitti:

Ok thanks, I re-checked now with my scopemeter instead of the electronics club's DMM, and there was slightly below 5Vpp 100Hz ripple on the otherwise steady +24Vdc rail (rail derived from full-wave recitified AC) when the solenoids were "on".

Couldn't speef up the filter capacitor(s) on the board, but after adding a 68ohm 10W resistor in series to the paralleled solenoids the ripple dropped to ~1Vpp, and the "problem" solenoid started working - reliably, even. :-)

Oddly the same solenoids worked fine on a bench top supply even down to

I guess, lesson learned, some door solenoids just don't like high rail ripple.

Thanks for the help and info both!

- Jan

Watch out how you wire them. If you common the power and return leads you may experience odd effects due to voltage drops. Ideally you should run separate wires from the power supply to each solenoid. If you don't, use larger than designed conductors if possible. Check what the drop out voltage is on each solenoid.