Two Stage Fan Switch - Simple Solution?
Discussion
Penelope Stopit said:
....If a vehicle has a fold-down or removable hood, the vehicle does not need a cooling fan running in the summer, this method is only for vehicles with a fixed roof What do you think to this?...
Not the case in practice I'm afraid. It rains here in summer so sometimes the roof has to go up and the poor ventilation means the windscreen can steam up, especially sitting traffic. So we need the blower the keep the screen clear.v8s4me said:
Penelope Stopit said:
....If a vehicle has a fold-down or removable hood, the vehicle does not need a cooling fan running in the summer, this method is only for vehicles with a fixed roof What do you think to this?...
Not the case in practice I'm afraid. It rains here in summer so sometimes the roof has to go up and the poor ventilation means the windscreen can steam up, especially sitting traffic. So we need the blower the keep the screen clear.Penelope Stopit said:
.... and the heat produced from the HRS would not be a problem would it ...
I thought we were talking about a convertible?...Penelope Stopit said:
....If a vehicle has a fold-down or removable hood, the vehicle does not need a cooling fan running in the summer, this method is only for vehicles with a fixed roof What do you think to this?...
Now I'm confused 
v8s4me said:
Penelope Stopit said:
.... and the heat produced from the HRS would not be a problem would it ...
I thought we were talking about a convertible?...Penelope Stopit said:
....If a vehicle has a fold-down or removable hood, the vehicle does not need a cooling fan running in the summer, this method is only for vehicles with a fixed roof What do you think to this?...
Now I'm confused That would work Leigh, but it's probably overkill. Having said that, small and cheap SMPS's are turning up all over the place such as there's one in every mains LED light you buy (and a noisy bugger it is too).
Probably a simpler alternative would just be a PWM switcher set at a 50% (or whatever) duty cycle for the slow setting. You could even have an adjuster knob to set the duty cycle and hence fan speed.
The reason for having PWM or an SMPS is that they can be over 90% efficient, so instead of a big fat resistor or rheostat (as below) sitting there getting hot, and being a fire risk, it's all nice and cool. Plus - less load on the alternator. Everyone's a winner!
Probably a simpler alternative would just be a PWM switcher set at a 50% (or whatever) duty cycle for the slow setting. You could even have an adjuster knob to set the duty cycle and hence fan speed.
The reason for having PWM or an SMPS is that they can be over 90% efficient, so instead of a big fat resistor or rheostat (as below) sitting there getting hot, and being a fire risk, it's all nice and cool. Plus - less load on the alternator. Everyone's a winner!
Edited by adam quantrill on Wednesday 15th March 08:38
Wedg1e said:
Penelope Stopit said:
ks. That's only relevant where electronic driver circuitry is involved. Stop overcomplicating things FFS.I love being able to help with stuff like this.
If there is anything else I can help you to understand please don't hesitate to post it and I will do my best
Alpha Omega said:
If there is anything else I can help you to understand please don't hesitate to post it and I will do my best
Yes there is. Why do people with a shiny new BTEC in electronics think they have all the answers? I let my 37 years of hands-on, real-world practical experience tell me that the miniscule amount of arcing caused by breaking the supply to a 12V relay is irrelevant and that I'll probably have retired before the afflicted switch fails.
This guy reminds me of that other gobs
te who only ever posted links to his own website full of ripped-off material on the flimsy pretext of helping people out despite not even owning one of the cars the bloody forum is aimed at.Wedg1e said:
Alpha Omega said:
If there is anything else I can help you to understand please don't hesitate to post it and I will do my best
Yes there is. Why do people with a shiny new BTEC in electronics think they have all the answers? I let my 37 years of hands-on, real-world practical experience tell me that the miniscule amount of arcing caused by breaking the supply to a 12V relay is irrelevant and that I'll probably have retired before the afflicted switch fails.
This guy reminds me of that other gobs
te who only ever posted links to his own website full of ripped-off material on the flimsy pretext of helping people out despite not even owning one of the cars the bloody forum is aimed at.Alpha Omega, you appear to share the same member page as Penelope Stopit. Are you the same person? Just curious.
Anyway, for anyone wondering about the original question, yes you can use a simple ballast resistor like the one shown above to reduce your fan speed. The only issue is where you mount the resistor because it does get a bit hot
.
Anyway, for anyone wondering about the original question, yes you can use a simple ballast resistor like the one shown above to reduce your fan speed. The only issue is where you mount the resistor because it does get a bit hot
.v8s4me said:
Alpha Omega, you appear to share the same member page as Penelope Stopit. Are you the same person? Just curious.
Anyway, for anyone wondering about the original question, yes you can use a simple ballast resistor like the one shown above to reduce your fan speed. The only issue is where you mount the resistor because it does get a bit hot.
Yes I am the same person, I changed my name to match my websiteAnyway, for anyone wondering about the original question, yes you can use a simple ballast resistor like the one shown above to reduce your fan speed. The only issue is where you mount the resistor because it does get a bit hot
.Try one of these: Governor 12V-40V 10A Pwm Dc Motor Speed Control http://www.ebay.co.uk/itm/like/122212707144
At £2.30 delivered it's not worth the hassle of trying to build your own.
it will run much cooler than the resistor and it wastes less power too - everyone's a winner!
You might even be able to reduce the switch current too, if it has an "enable" line...
Ebay item 112335704679 is even cheaper but 3A might not be enough.
At £2.30 delivered it's not worth the hassle of trying to build your own.
it will run much cooler than the resistor and it wastes less power too - everyone's a winner!
You might even be able to reduce the switch current too, if it has an "enable" line...
Ebay item 112335704679 is even cheaper but 3A might not be enough.
adam quantrill said:
Try one of these: Governor 12V-40V 10A Pwm Dc Motor Speed Control http://www.ebay.co.uk/itm/like/122212707144
At £2.30 delivered it's not worth the hassle of trying to build your own.
it will run much cooler than the resistor and it wastes less power too - everyone's a winner!
You might even be able to reduce the switch current too, if it has an "enable" line...
Ebay item 112335704679 is even cheaper but 3A might not be enough.
This is amazingAt £2.30 delivered it's not worth the hassle of trying to build your own.
it will run much cooler than the resistor and it wastes less power too - everyone's a winner!
You might even be able to reduce the switch current too, if it has an "enable" line...
Ebay item 112335704679 is even cheaper but 3A might not be enough.
adam quantrill said:
........Try one of these: Governor...
Thanks for the tip. Unfortunately I've "adapted" my switch panel now so I've got an auxiliary rad fan switch where the ciggy lighter was. Your little gadget might have fitted the ciggy lighter hole and I could have used the heater control slot for the auxiliary fan. Never mind, I'm sure there will be a next time. My fan draws just over 12A on full power, this unit is rate at 10A so would it be OK? At that price I think I'll buy one anyway and experiment with it. What's the worst that could happen? 
Edited by v8s4me on Monday 15th May 20:37
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