FBH remote operation circuit - Page 2

FROGGY · 30th January 2009, 18:46

Nick As the operating voltage of most LED’s is between 1.6 and 4.5V (depending on colour), you would need a small circuit of some description to provide the correct voltage from your 12V supply.

You can buy LEDs with built-in dropper resistors but then the light intensity is set.

If I’m telling you something you already know ignore the following!

You can calculate the dropper resistor value (R) required by using the formula: R = (VS - VL) / I, where VS is the supply voltage, VL is the LED voltage, and I is the maximum LED current.

Use the nearest standard value resistor to the calculated result, but never drop below the calculated value, otherwise the LED will burn out quickly.

Being a diode you shouldn’t have any problems with it in circuit with the relay output to the FBH.

HTH

Mick

NikTheGeek · 30th January 2009, 19:49

Quote:

Originally Posted by FROGGY

If I’m telling you something you already know ignore the following!

I should have known, being a radio ham for 20 years, but one forgets these things!

Anyway, yes, you're right, a LED will be fine. And being lazy, I could probably just get one of those flashing pretend alarm-type 12v ones for a quid!

tnx

Nick

black olive · 30th January 2009, 20:46

why not use the relay to switch another douple pole relay so you have a pole for the fb and a pole for the led circuit. seems a bit overkill though- by the time youve bought relaay led and resitor and fannied about you may as well get the timer .

-Joe · 31st January 2009, 14:52

Is easy to leave fbh on by mistake.

Timer is sure fire way to ensure it always goes off when you leave the car.

Going to fit a red led to dash next to temp dials to indicate fbh overide on.

NikTheGeek · 31st January 2009, 18:17

Got a timer kit and built it. Out of the box it does 0-15 mins (actually 0-9 mins as tested). I've increased the value of a capacitor and now got between 0-40 mins.

So, before I varnish it all and put it in the car, what is a "typical" time one would run a parking heater for? 15mins? 20mins? 30mins?

Many thanks

Nick

Greeners · 31st January 2009, 18:20

Quote:

Originally Posted by NikTheGeek

Got a timer kit and built it. Out of the box it does 0-15 mins (actually 0-9 mins as tested). I've increased the value of a capacitor and now got between 0-40 mins.

So, before I varnish it all and put it in the car, what is a "typical" time one would run a parking heater for? 15mins? 20mins? 30mins?

Many thanks

Nick

Depends on how cold it is....usually let mine run for 30 minutes

CDTi · 31st January 2009, 19:25

I find 15 minutes usually clears my windows and makes the interior nice and toasty.

black olive · 31st January 2009, 21:54

30 minutes will cover you for the coldest of days- once up to temp the fbh goes into tickover mode anyway.

noticed you are a radio ham and just up the road from me- Im licensed (G4 WCS- or Bogs !!) mainly active on 6m, so used to talking to myself !!

NikTheGeek · 31st January 2009, 22:19

Quote:

Originally Posted by black olive

30 minutes will cover you for the coldest of days- once up to temp the fbh goes into tickover mode anyway.

noticed you are a radio ham and just up the road from me- Im licensed (G4 WCS- or Bogs !!) mainly active on 6m, so used to talking to myself !!

Set for 24 mins - don't ask why, I timed it and it happened to be on that and I couldn't be bothered changing it to 20 or 25 as its a potentiometer and not that accurate anyway!

FYI: G7IZR

73 & 10-10

Nick

NikTheGeek · 31st January 2009, 22:26

Quote:

Originally Posted by CDTi

I find 15 minutes usually clears my windows and makes the interior nice and toasty.

You say it clears your windows and makes the interior nice and toasty. How? I've heard before that they are supposed to swith the ATC panel on in the car, but mine doesn't. Or at least it doesn't light up to indicate it is on. I haven't actually sat in the car with the FBH running to see if warm air comes out of the vents, but I couldn't hear the air vent blowers when I was outside of the car fiddling with it all.

Does the ATC illuminate or is it just on, in the background, minding its own business, blowing air in to the car?

Or, after all that, do I still have a fault? Its the later 9xxxxx FBH that I have.

Mind you, at least when I start the engine and manually turn on the ATC, the air is warm coz the engine is warm!

Nick

30th January 2009, 18:46	#11
FROGGY I really should get out more....... MG ZT CDTI Join Date: Sep 2007 Location: 17500 REAUX, CHARENTE-MARITIME Posts: 2,749 Thanks: 2 Thanked 133 Times in 90 Posts	Nick As the operating voltage of most LED’s is between 1.6 and 4.5V (depending on colour), you would need a small circuit of some description to provide the correct voltage from your 12V supply. You can buy LEDs with built-in dropper resistors but then the light intensity is set. If I’m telling you something you already know ignore the following! You can calculate the dropper resistor value (R) required by using the formula: R = (VS - VL) / I, where VS is the supply voltage, VL is the LED voltage, and I is the maximum LED current. Use the nearest standard value resistor to the calculated result, but never drop below the calculated value, otherwise the LED will burn out quickly. Being a diode you shouldn’t have any problems with it in circuit with the relay output to the FBH. HTH Mick __________________ http://i200.photobucket.com/albums/a...ps628d4119.jpg IN THE BLACK NOW

30th January 2009, 20:46	#13
black olive I really should get out more....... 260 SE vin 214 ( last mark 1 260 ) Join Date: Dec 2006 Location: Lancashire Posts: 2,009 Thanks: 1 Thanked 8 Times in 4 Posts	why not use the relay to switch another douple pole relay so you have a pole for the fb and a pole for the led circuit. seems a bit overkill though- by the time youve bought relaay led and resitor and fannied about you may as well get the timer . __________________ [SIGPIC][/SIGPIC]

31st January 2009, 14:52	#14
-Joe Avid contributor Rover 75 Classic SE 1.8T Join Date: Dec 2008 Location: wink Posts: 135 Thanks: 0 Thanked 20 Times in 15 Posts	get a timer Is easy to leave fbh on by mistake. Timer is sure fire way to ensure it always goes off when you leave the car. Going to fit a red led to dash next to temp dials to indicate fbh overide on.

31st January 2009, 19:25	#17
CDTi This is my second home No longer in the MGR club Join Date: Nov 2006 Location: Tipperary Posts: 3,933 Thanks: 35 Thanked 51 Times in 35 Posts	I find 15 minutes usually clears my windows and makes the interior nice and toasty. __________________ 'Tis better to be silent and be thought a fool, than to speak and remove all doubt.

31st January 2009, 21:54	#18
black olive I really should get out more....... 260 SE vin 214 ( last mark 1 260 ) Join Date: Dec 2006 Location: Lancashire Posts: 2,009 Thanks: 1 Thanked 8 Times in 4 Posts	30 minutes will cover you for the coldest of days- once up to temp the fbh goes into tickover mode anyway. noticed you are a radio ham and just up the road from me- Im licensed (G4 WCS- or Bogs !!) mainly active on 6m, so used to talking to myself !! __________________ [SIGPIC][/SIGPIC]

31st January 2009, 18:17	#15
NikTheGeek Gets stuck in 2002 Range Rover P38 Join Date: Dec 2008 Location: Wigan Posts: 593 Thanks: 0 Thanked 0 Times in 0 Posts	Got a timer kit and built it. Out of the box it does 0-15 mins (actually 0-9 mins as tested). I've increased the value of a capacitor and now got between 0-40 mins. So, before I varnish it all and put it in the car, what is a "typical" time one would run a parking heater for? 15mins? 20mins? 30mins? Many thanks Nick