Low voltage shower fan delay timer thingymajig

[TandC]

I'm after a delay timer for my shower extractor fan - but do they exist in a "low voltage in - low voltage out" format?   The ones I can easily find are all for 240v, incorporating a transformer to drop the voltage down from 240 to 12, before the timer function.

 

I just want something that will come on with the bathroom lights, run the extractor for the duration they are left on and then turn itself off say 20mins after the lights are turned off.

 

Something like this - but which will work off the 12v lighting 

https://www.amazon.co.uk/Manrose-Primeline-Transformer-Adjustable-T12T/dp/B00E98TB1I/ref=asc_df_B00E98TB1I/?tag=googshopuk-21&linkCode=df0&hvadid=223237768057&hvpos=&hvnetw=g&hvrand=17500806529905712466&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9046128&hvtargid=pla-421823535565&psc=1

 

 

Or - is it possible to "hack" one of these and just bypass the transformer element -  i guess i could buy one and open it up and take a looksie inside. 

 

 

I want to use one of these fans - as I find the larger domestic orientated ones are a bit large and bulky. 

https://marine-electricals.co.uk/product/12v-extractor-fan-no-light-marine-leisure/

 

 

I expect there is a pretty simple 12v timer circuit I could make up if i had the electricwizzardy know-how 

Edited July 22, 2023 by TandC

[Jen-in-Wellies]

One I came across some years ago in a project for some friends are the U6046B and U6047B chips, which are 12V automotive chips typically used to time a rear window demister and turn it off after a settable time. Ideal for your circumstances, with a relay to switch the load, but needs a little elecricary wizardry to turn in to what you want.

[GUMPY]

You could revert back to building something with a 555 timer chip🤔

This may work

 

DC 5V/12V/24V Delay Timer Relay, Self-locking Delay On Off Time Switch Super 555 Timer (DC12V ) https://amzn.eu/d/5DPqpD6

[Jen-in-Wellies]

15 minutes ago, TandC said:

Something like this - but which will work off the 12v lighting 

https://www.amazon.co.uk/Manrose-Primeline-Transformer-Adjustable-T12T/dp/B00E98TB1I/ref=asc_df_B00E98TB1I/?tag=googshopuk-21&linkCode=df0&hvadid=223237768057&hvpos=&hvnetw=g&hvrand=17500806529905712466&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9046128&hvtargid=pla-421823535565&psc=1

 

 

Or - is it possible to "hack" one of these and just bypass the transformer element -  i guess i could buy one and open it up and take a looksie inside. 

Quite likely. These days, the 240V to low voltage is more likely to be a buck converter than a transformer. The internal electronics are most likely to be 12V, 5V, or 3.3V, or possibly a mixture. Needs some investigation and probing with a voltmeter while powered up to tell, but can then be hacked to work from 12V. Thing is that the skills involved in doing so are such that you could just as easily build such a simple thing from scratch yourself.

[GUMPY]

Or this

Time Delay Relay Module, Delay Relay Module 5v 12v 24v Timer Switch 50ma 0.01s-9999min, Delay Off Cycle Timer Module Timer Relay with Lcd Display (1) https://amzn.eu/d/j4m1QYc

 

555 timers might be old tech but do the job

 

Google "555 timer kit" for more results

 

[Alan de Enfield]

Just a 'non-technical' option.

 

I use these on our car-park lights, timer is adjustable and works on a 'leaky vacuum' (no electronics). Push the button ato switch on and it slowly creeps back 'out' and when full 'out switches off the light.

 

Duration is variable, some to a max of 5 minutes, others longer.

 

Example :

 

Vacuum Time Lag Light Switch | Elkay (400A) (tlc-direct.co.uk)

 

Elkay 400A Pneumatic Time Delay Switch - Screwfix

 

 

This one is 20 seconds to 20 minutes duration but is an 'electronic' option

CP Electronics Push Button Ellipse Time Lag Switch (ELLIPSE) | CEF

 

They are all 2-wire 230v but would work on 12v DC.

[blackrose]

I can't help thinking that some people do like to over-complicate things. If your memory is that bad, you could just get yourself a digital timer from eBay for a few quid to remind you to turn off the extractor. 🤣

 

https://www.ebay.co.uk/itm/334710930514?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=LUv5QTRmQrC&sssrc=4429486&ssuid=SV_sF0T7SiS&var=&widget_ver=artemis&media=COPY

[Jen-in-Wellies]

3 minutes ago, blackrose said:

I can't help thinking that some people do like to over-complicate things. If your memory is that bad, you could just get yourself a digital timer from eBay for a few quid to remind you to turn off the extractor. 🤣

 

https://www.ebay.co.uk/itm/334710930514?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=LUv5QTRmQrC&sssrc=4429486&ssuid=SV_sF0T7SiS&var=&widget_ver=artemis&media=COPY

Or tie the shower room door knob to the extractor pull cord. Open the door and it turns off the fan!

[Sea Dog]

10 minutes ago, blackrose said:

If your memory is that bad, you could just get yourself a digital timer from eBay for a few quid to remind you to turn off the extractor. 🤣

Presumably you're recommending this for the hard of hearing - for the rest of us, the constant "WHOO" noise denies us any option to forget the damned thing is on. 

[Jen-in-Wellies]

16 minutes ago, Jen-in-Wellies said:

Or tie the shower room door knob to the extractor pull cord. Open the door and it turns off the fan!

I know I wrote this as a joke, but it is actually a workable solution. With a pull cord switch and a length of suitable stretch bungee in the system it could be made practical. Open the door to go in and close it behind you, the fan comes on. When you leave, opening and closing the door turns the fan off. No electronics and really cheap.

[adrianh]

Plenty of 12 volt delay timers on ebay although some will need an enclosure box.

Broyce manufacture DIN mounted timers ( they fit standard domestic type fuse enclosures ) that operate on 12 volts dc also others if you search

[ditchcrawler]

8 hours ago, TandC said:

I'm after a delay timer for my shower extractor fan - but do they exist in a "low voltage in - low voltage out" format?   The ones I can easily find are all for 240v, incorporating a transformer to drop the voltage down from 240 to 12, before the timer function.

 

I just want something that will come on with the bathroom lights, run the extractor for the duration they are left on and then turn itself off say 20mins after the lights are turned off.

 

Something like this - but which will work off the 12v lighting 

https://www.amazon.co.uk/Manrose-Primeline-Transformer-Adjustable-T12T/dp/B00E98TB1I/ref=asc_df_B00E98TB1I/?tag=googshopuk-21&linkCode=df0&hvadid=223237768057&hvpos=&hvnetw=g&hvrand=17500806529905712466&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9046128&hvtargid=pla-421823535565&psc=1

 

 

Or - is it possible to "hack" one of these and just bypass the transformer element -  i guess i could buy one and open it up and take a looksie inside. 

 

 

I want to use one of these fans - as I find the larger domestic orientated ones are a bit large and bulky. 

https://marine-electricals.co.uk/product/12v-extractor-fan-no-light-marine-leisure/

 

 

I expect there is a pretty simple 12v timer circuit I could make up if i had the electricwizzardy know-how 

A starting point Power Delay Relay Car Rear View Camera Power Delay Timer Relay Filter Rectifier 640411073455 | eBay

 

or a bit longer 

EASY TO USE CAR TIMER SWITCH RELAY 1-150 SEC Delay OFF 12V 20A DIRECT 12V OUT | eBay

Edited July 22, 2023 by ditchcrawler

[pig]

I use a pneumatic switch like Alan d’E suggests, but I’ve found it needs a 12v relay in the circuit, or the contacts don’t last long on 12volts.

[blackrose]

12 hours ago, Sea Dog said:

Presumably you're recommending this for the hard of hearing - for the rest of us, the constant "WHOO" noise denies us any option to forget the damned thing is on. 

 

Depends how loud the fan is, you don't have to be hard of hearing not to hear a small computer fan for example. I've left my manrose 12v extractor fan on for an hour without realising when the TV has been on masking the sound for example, but 5 amps over an hour isn't a problem.

[ditchcrawler]

5 minutes ago, blackrose said:

 

Depends how loud the fan is, you don't have to be hard of hearing not to hear a small computer fan for example. I've left my manrose 12v extractor fan on for an hour without realising when the TV has been on masking the sound for example, but 5 amps over an hour isn't a problem.

If its drawing 5 amps I would expect it to sound like a helicopter landing

[TandC]

Thanks for the replies.  I know - over-engineering... but then having a bit of  run time on the fan post-shower is a good feature to help excess moisture out of the boat and it not rely upon someone then remembering to go back and turn the fan off. 

 

I shall experiment with  a 555 unit - something that could be tucked out of the way...   it's not vital, but the cables are going in now so I'm going to put in two options. Timed, and straight operated by the shower light.