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paralleling of solenoid cabinet locks?

J

Jan Wagner

Jan 1, 1970
0
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
http://users.tkk.fi/~jwagner/electr/tmp/solenoid-ctrl.gif
where the solenoid(s) are connected to JP1.

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
 
D

Dan Hollands

Jan 1, 1970
0
Jan Wagner said:
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
http://users.tkk.fi/~jwagner/electr/tmp/solenoid-ctrl.gif
where the solenoid(s) are connected to JP1.

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


You need to measure the voltage across the pins at JP1 and at the solonoids.
Based on the above, the probable explaination is that the 100 ohm load is
causing a drop in voltage below what the other solonoid requires.

BTW when you measured the 200k did you try reversing the ohmeter leads. 200k
sounds unreasonable. Maybe there is a diode in series.


--
Dan Hollands
1120 S Creek Dr
Webster NY 14580
585-872-2606
[email protected]
www.QuickScoreRace.com
 
S

Sjouke Burry

Jan 1, 1970
0
Jan said:
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
http://users.tkk.fi/~jwagner/electr/tmp/solenoid-ctrl.gif
where the solenoid(s) are connected to JP1.

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.
 
J

Jan Wagner

Jan 1, 1970
0
Dan Hollands kirjoitti:
You need to measure the voltage across the pins at JP1 and at the solonoids.
Based on the above, the probable explaination is that the 100 ohm load is
causing a drop in voltage below what the other solonoid requires.

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
10Vdc.

I guess, lesson learned, some door solenoids just don't like high rail
ripple.
BTW when you measured the 200k did you try reversing the ohmeter leads. 200k
sounds unreasonable. Maybe there is a diode in series.

200k either way, at least with the DMM. Probably its fooled by the
inductance. Scopemeter says ca 300ohm, bench top supply's Vout/Iout gave
~250ohm, which sound more like it.

Thanks for the help and info both!

- Jan
 
H

Homer J Simpson

Jan 1, 1970
0
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. :)

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.
 
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