DIY 12V Delay - Possible?

[DolbyR]

So i want to add a delay to keep electricity running to my car's electric windows for atleast 30 secs after turning off the ignition. Is it possible to make one or should i just go on a part store and purchase one?

 

[AndrewT]

Hi,
you must have some parts store to meet that requirement.

Search for time delays here and add a relay to feed the windows.
There should be lots of options.

 

[dnsey]

There is indeed an aftermarket device which closes the windows when the ignition is switched off, if you prefer to buy one.
It would be a simple project to design and build, though (555 and thyristor comes to my old-school mind, but no doubt some would use a PIC etc.) Just bear in mind that car batteries can produce dangerous amounts of current - fuse appropriately!

 

[quasi]

Do you want the windows to go up automatically when you turn the ignition off or do you just want the ability to wind them up within 30 seconds manually?

If the latter is true and you only need approximately 30 seconds then a discharging capacitor on the base of a transistor driving a relay will do the job. Total cost $5 - $10 US (plus time).

Cheers

 

[DolbyR]

Quasi: Thats exactly what im searching, i know there are these "boxes that are ready for this but im too lazy to start searching them, its easier for me to go in the electronics shop around the corner

I guess that changing the value of the cap i could even get different dealy times, am i correct?

 

[DolbyR]

Here's actually one that would be really good http://www.electronics123.com/s.nl/it.A/id.344/.f?sc=8&category=44 my local dealer unfortunately doesnt sell the Courtesy Delay kit anymore, looks quite simple though, if i woulf just have the schematic it would be possible...unless it needs PIC programming

 

[gmphadte]

Here is a simple shematic.
This one is for delaying the door lights and fits across one of the door switches. Modify it to suit your reqs.

Gajanan Phadte

 

[jamesjung21]

Here's an even better one from Jaycar Electronics:

http://www.jaycar.com.au/productVie...d2=&pageNumber=&priceMin=&priceMax=&SUBCATID=

I can send these to you if you can send me the Cost + Shipping via PayPal.

AUD $18.95 is currently US $14.10, and the shipping cost is about $7.50 via airmail for one kit, and you can save the overall shipping cost if you order more than one. (two kits would cost about $10)

Let me know if you are interested: sendtojamesj@gmail.com

Cheers,
James

 

[DolbyR]

James: Sorry, the offer is great but PayPal is not working here.

i guess ill try with Gajanan's circuit, the local shiop doesnt have the BC328, only BC327 so i must still check how different that one is or if i'll just place them an order from Farnell.

 

[gmphadte]

Use any pnp transistor like 2N2907, instead of BC
The delay time is 10-12 Secs.

 

[quasi]

The circuit posted by Gmphadte whilst perfect for holding up interior lights is not suitable for providing a delay for power windows. I can think of 2 main reasons for this.

1. The currents drawn by the motors on startup will far exceed the capability of the 2N3055 and probably destroy it. During the fade-out period of this circuit, the current drawn by the motor will actually increase (especially when it finally stalls).

2. The back EMF will probably destroy the transistor, and because of the polarity reversal on these motors (up/down) it is not easy to fix.

A relay is the safest way to solve this and the circuit attached is what I had in mind. Simple I know, but if only rough timing is required then it's adequate and cheap.

Choose R1 & C1 to achieve the delay required.

Cheers