# (HELP) 555 Timer that flickers on and off a 12V 2A linear solenoid electromagnet

#### SageRamsammy

Joined Jun 19, 2016
16
hi, I am trying to make a 555 timer circuit that can flicker on and off my solenoid, (2 seconds on, 2 seconds off, repeating) but I barely have experience with electrical engineering. The whole purpose of this is to click a button. Can anyone give me a circuit diagram showing me how to set this up with a 555 timer and proper resistors? I tried using an LED flickering 555 timer circuit diagram I found, and it works when I use an LED, but when I plug my solenoid in, nothing happens. Help would be very much appreciated

#### bushrat

Joined Nov 29, 2014
209
555 timer can power up an LED, but it does not have enough current to power up your solenoid.
For proper timing, just google "555 timer calculator"
As for driving your solenoid, you must use a transistor as a switch, like so:
(ignore pin numbers and resistor values in this pic)

#### SageRamsammy

Joined Jun 19, 2016
16
what do you mean by "driving my solenoid"?

#### SageRamsammy

Joined Jun 19, 2016
16
555 timer can power up an LED, but it does not have enough current to power up your solenoid.
For proper timing, just google "555 timer calculator"
As for driving your solenoid, you must use a transistor as a switch, like so:
(ignore pin numbers and resistor values in this pic)
*what I said above

#### Alec_t

Joined Sep 17, 2013
13,223
You will also need a reverse-biased diode across the solenoid coil, otherwise your TIP122 will be fried by the back-emf pulses generated each time the solenoid is switched off. The diode should be rated to handle the same current that the solenoid draws. What are the voltage/current/resistance specs of the solenoid? (Edit: just noticed the figures in the thread title).

Last edited:

#### bushrat

Joined Nov 29, 2014
209
...enough current to power it up.
555 timer can only provide 20-30 mA or current, you need 2A. the transistor you use must handle so much power, as regular transistor will go "poof" or just melt.

#### SageRamsammy

Joined Jun 19, 2016
16
You will also need a reverse-biased diode across the solenoid coil, otherwise your TIP122 will be fried by the back-emf pulses generated each time the solenoid is switched off. The diode should be rated to handle the same current that the solenoid draws. What are the voltage/current/resistance specs of the solenoid?
12V
5.6 Ohm resistance

#### SageRamsammy

Joined Jun 19, 2016
16
12V
5.6 Ohm resistance
do you have any videos or instructions for this? Sorry I really don't know anything about circuits, I'm just trying to build this project haha.

#### dl324

Joined Mar 30, 2015
15,419
when I plug my solenoid in, nothing happens.
What is the full part number of the 555 timer you're using?

The bipolar version (NE555, LM555, and similar) can sink or source 200mA. CMOS variants will have much lower drive capability.

What is the coil resistance of the solenoid? A part number would be helpful.

EDIT: Just saw the posts giving solenoid particulars. Regardless of the timer you're using, you require a transistor to drive the solenoid coil. Like the circuit in post #2.

#### SageRamsammy

Joined Jun 19, 2016
16
What is the full part number of the 555 timer you're using?

The bipolar version (NE555, LM555, and similar) can sink or source 200mA. CMOS variants will have much lower drive capability.

What is the coil resistance of the solenoid? A part number would be helpful.

EDIT: Just saw the posts giving solenoid particulars. Regardless of the timer you're using, you require a transistor to drive the solenoid coil. Like the circuit in post #2.
Is there a way to create the circuit I'm looking for without a 555 timer?

#### SageRamsammy

Joined Jun 19, 2016
16
What is the full part number of the 555 timer you're using?

The bipolar version (NE555, LM555, and similar) can sink or source 200mA. CMOS variants will have much lower drive capability.

What is the coil resistance of the solenoid? A part number would be helpful.

EDIT: Just saw the posts giving solenoid particulars. Regardless of the timer you're using, you require a transistor to drive the solenoid coil. Like the circuit in post #2.

#### SageRamsammy

Joined Jun 19, 2016
16
beautiful. Couple questions tho bc I'm really nooby to this stuff. What is "Cf" "D2" and "Q1"?

#### bushrat

Joined Nov 29, 2014
209
Cf - regular 10 nanofarad capacitor, D2 diode, buy this specific number, Q1, transistor that can handle 2A of current, buy this specific number.