NE555 with solenoid

[Demon]

I'd like to activate a solenoid for a brief moment. Does this timer look correct?

9978

- I added a large cap alongside the solenoid; value is just preliminary.
- the opto is to isolate the solenoid, it will be on a separate 5V line.
- the 10K pot is just to start, I'll bump up to 25K if 110ms is not enough time.


The solenoid will eventually be driven by a PIC, this is only for testing purposes (like figuring out exactly how much correct this thing consumes, how short a pulse of 5V it will accept - I have no datasheet).

Never having used a solenoid before, a quick touch of wire makes it pulse several times. I assume it's normal that it cycles non-stop if I leave it connected - I figure it's the coil charging and discharging.

It's one of these tiny 5V solenoids:

https://www.aliexpress.com/item/1005002278950915.html

[louislouis]

I’m using this circuit.
When the button is pressed, the relay switches on for one second and then turns off.
It doesn’t matter whether the button is pressed briefly or held down - the circuit always activates the relay for a fixed pulse duration.
9980

[Demon]

Can you control duration with this design?

[louislouis]

Of course. By changing the resistance R3, or the value of the capacitor C1, or a combination of both.

[amgen]

data sheet said 5v solenoid is about .7 amps.... 700 ma, and that opto thing data said 30 ma continous..... need a better driver ckt, can use a transistor or a DIP ss relay good for up to 1 amp

[Demon]

data sheet said 5v solenoid is about .7 amps.... 700 ma, and that opto thing data said 30 ma continous..... need a better driver ckt, can use a transistor or a DIP ss relay good for up to 1 amp


Yeah, I quickly dropped the MCT6 when I checked the specs.

I toyed with the 2N7000, but I've since switched to a IRF730A mosfet; works flawlessly (I just have to properly calculate the base resistor - I just slapped a 1K in there to test).

JLCPCB has a dual channel IRF730A for only $0.13 - $0.20 (depending who's I take).

https://jlcpcb.com/partdetail/6129882-IRF7307TR_UMW/C5346816


Note: I will be pulsing the solenoid a single burst (it's an electrical breaker for MSFS console), so maybe the 2N7000 might safely work. I have no clue, just winging it right now.

[Demon]

data sheet said 5v solenoid is about .7 amps....


Yeah, about that. Solenoid barely moves at 5V. I just tested on a bench PS and it really starts working closer to 7V. 9V and it gives a nice "snap".

I'd love to find a transistor like the 2N7000 that can take a bit more current (NPN, over 800mA).

I'll put up a video later. I also have a rotary switch to document (ignition switch with a spring-loaded return for the "START" position), along with a gauge (stepper) on soonday.