12v pulse into 12v supply help needed

Alec_t

Joined Sep 17, 2013
14,280
Well it's one way to go. Others here may have alternatives. If the lock actuation proves too brief you could increase the value of R7 (to, say, 100k).
 

Thread Starter

nooby

Joined Nov 16, 2013
13
I would rather have a pot for adjustable time. It will take some experimenting but I'm thinking around 5-10 seconds max will be ok so I'll have to play with values.

It will take me a while to get the MOSFET so i will get back to you. I had perhaps considered a relay but i will bow to your expertise.

I asked if it was still the best way to go because you mentioned maybe not needing some parts anymore due to the coils resistance. I wasnt questioning your circuit accuracy.
I'm grateful for all the help youve given me.
 

Alec_t

Joined Sep 17, 2013
14,280
I would rather have a pot for adjustable time.
My circuit already has one (100k), which should give a pulse adjustable up to ~11.5 sec long. If that time proves insufficient R7 could be increased.
you mentioned maybe not needing some parts anymore due to the coils resistance
Now that we know the coil will be drawing ~0.4A those parts are needed.
 

Thread Starter

nooby

Joined Nov 16, 2013
13
I see, thankyou. I said i was a noob lol.

Thankyou so much for your help. I will order the bits i dont have and post back my results. I warn you it could be messy but I'll try my best he he.
 

Thread Starter

nooby

Joined Nov 16, 2013
13
Sorry to be a pain but I'm going through the circuit for a parts list and am getting a little muddled up, if you could clarify a couple of things for me it would be great.

What is D3? Is it a 1N5818 with the software putting the label in the wrong place?

R1, R5 and R6 just have a value, are these just ohm's?

R2,3,4 and 7 say 4k7, are those 4.7k just labeled differently to what I'm used to?

C1 and 4 say 10n and 100n respectively but ive only seen uf on caps before, is it just another way of putting uf or is it somthing different?

Sorry for all the questions but before i make the day long return trip to my nearest parts store i just want to be sure on what I'm getting.

Thanks for your help.
 
Last edited:

Alec_t

Joined Sep 17, 2013
14,280
D1 is shown as a 1N5818, but that may be a bit OTT. The type isn't critical, provided it's rated for > ~0.5A. A 1N400x (e.g. 1N4002) might be easier/cheaper to source. Likewise almost any silicon diode will do for D1 and D2. So all of D1-D3 could be, for example, 1N4002.
R1, R5 and R6 just have a value, are these just ohm's?
Yes. Standard 0.25W types are adequate for all the resistors.
is it just another way of putting uf or is it somthing different?
'n' or 'nF', for a cap value, denotes 'nanofarad'. 1nF = 0.001uF.
C2,C3,C5 are electrolytic caps and should have a working voltage rating > 12V. I suggest 25V.
C1,C4 are ceramic or plastic-film type.
While getting parts get an extra 100nF cap (not shown in my schematic) to connect in parallel with C3 and as close as possible to the supply pins of the IC.
Take anti-static precautions when handling the MOSFET M1.
The pot should have its wiper connected to one or other of its end terminals to make a variable resistor as shown.
 

Thread Starter

nooby

Joined Nov 16, 2013
13
Similarly to the other one you sent via pm it looks like that unit operates when power is applied and operates from that power source.
That is not what im after and will not work in my application.
Thanks for the suggestion though and appolagies if that's not the way it works.
I also must add that as ive mentioned earlier, im in the uk so ordering from elsewhere will end up expensive.

If a kit or switch working like that can be altered and used then ive got a couple of vellman kits knocking around i could use (mk111 universal timer) but i dont understand well enough to convert that kit into what i need.

I'm more than happy with the circuit posted for me and have most of the bits on the shelf already.
 
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