Completed Project 24v to 5v logic and 12v solenoid actuation.

Thread Starter

PathogenIX

Joined Oct 14, 2020
21
Hi all

I have a device that outputs 24V, and I want to lower that voltage to 5V as well as actuate a 12v solenoid on full voltage.

This is the original schematic and it works fine. I have built this circuit and have it connected and proved its usability
schematics-2-768x448.png

Now I need to add the capability to actuate a solenoid only when the input voltage is @ 24v and close when lower than 24v
I have tried to create something here but i feel i'm missing a big part

Untitled.png


J1 = Bias power input (24v input)
J2 = Fan control input (24v (PWM?))
J3 = Fan output
J4 = 12v solenoid 250mA (Open @ =12v / Close @ >12v)
J5 = 0v-5v laser output

JP1 = SPDT Switch

+5v = Connected together
+12v = Connected together
Gnd_1 = Connected together
Gnd_2 = Connected together

Can someone tell me what i've done wrong. If this circuit will work? If its flawed entirely?
 

eetech00

Joined Jun 8, 2013
2,032
Opto U? should have a separate 2K2 limiting resistor. The resistor should be connected between opto u? and "air_assist_switch". Move the air_assist_switch pin 1 to the junction of JP1/R1.

R5 should be about 1k ohms.
 
Last edited:

Thread Starter

PathogenIX

Joined Oct 14, 2020
21
Where’s the requirement for fast switching? The response time of the solenoid is likely much larger than the BJT or MOSFET switching time.
That is a very fair point... Got any examples of circuits/components that will only trigger on when a voltage of 12vOR5v is applied and switch off when it drops below 12vOR5v?
 

Thread Starter

PathogenIX

Joined Oct 14, 2020
21
Hmm very confused right now...

Built part of the circuit on a BB and just what? like what? why? J4 = 0v to 0.5v consistently shifting up and down...

Why isn't this working as required? Have i been stupid in assuming an opto can transfer voltage change across itself? Does it only transfer current change? (Literally googled that question and got 100 questions that had nothing to do with it.... )
:confused:If im right and i have been a stupid fool what could i use to transfer voltage changes? Comparator? Any example?

Please help.

Untitle2324d.png
 

Thread Starter

PathogenIX

Joined Oct 14, 2020
21
New update =
One issue... Is Q1 inverting the input?
Also why after 10seconds of power on does this circuit seem to cycle the solenoid on rapidly then die down.... Then repeat with each cycle getting faster....222222.png
 

djsfantasi

Joined Apr 11, 2010
6,947
New update =
One issue... Is Q1 inverting the input?
Also why after 10seconds of power on does this circuit seem to cycle the solenoid on rapidly then die down.... Then repeat with each cycle getting faster....View attachment 219717
Yes, Q1 is inverting the input, kind of. When the input is at Gnd, the Drain isn’t connected. When there is a voltage input to the Gate, the Drain is connected to Gnd through the Source. Since you’re driving a solenoid, this should work. However if you want, you can add a pull-up to the Drain of the MOSFET.

I didn’t check the datasheet for the MOSFET, but it is a logic level n channel MOSFET. since you are driving it with 24V, check to see if the IRL540 will operate at that voltage.
 

Thread Starter

PathogenIX

Joined Oct 14, 2020
21
Yes, Q1 is inverting the input, kind of. When the input is at Gnd, the Drain isn’t connected. When there is a voltage input to the Gate, the Drain is connected to Gnd through the Source. Since you’re driving a solenoid, this should work. However if you want, you can add a pull-up to the Drain of the MOSFET.

I didn’t check the datasheet for the MOSFET, but it is a logic level n channel MOSFET. since you are driving it with 24V, check to see if the IRL540 will operate at that voltage.
Operation voltage as in? Ground-Source Voltage = +-16v
So i ran it +8v over... Oops..

This is the full circuit.
Could I tap into the 5v signal like this and use that to switch the MOSFET? Or could that compromise its ability to activate J5?
pasta.pngpasta.png
 

Thread Starter

PathogenIX

Joined Oct 14, 2020
21
Ok I reached a point where I thought I had this done. Built on a Breadboard and then found I was wrong. This is my current design cut into sub-sections.
Can anyone help out?

Help.png
 
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