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post #1 of (permalink) Old 09-12-2003, 05:13 PM
thejunker
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Fan Wiring Question w/ Indcators

OK all you wiring guru's, take a look at this.

I am wiring in an electric fan this weekend, flex-a-lite model 575. I could not fit the SPAL fan, so had to go with FAL.

Here are links to the product page and the manual page for more info:

Product & Manual

In the drawing below, the fan controller has been simplified. The input marked as Power is the + source for the fan. The input marked as Manual, is an input that overides the thermostat control, and turns on the fan.

The Objective

1) Install a switch that performs 3 functions:

Normal (temp controlled operation)
On (always on opperation)
Off (never on operation)

2) Have 2 indicator lights

One will be on in the "On" position
One will be flashing in the "Off" position

At the bottom of this post, is the diagram I drew for this.

Questions

1) Will this work as drawn? If not, why?

2) Is a 660 ohm resistor going to work to drop the voltage low enough for the 5V LED?

3) What diodes should I use to isolate the two "on" positions?

Thanks for all your help!


Attached Images
File Type: gif 1186021-wiringDiagramFan.gif (7.0 KB, 17 views)
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post #2 of (permalink) Old 09-12-2003, 07:41 PM
thejunker
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Re: Fan Wiring Question w/ Indcators

Oh, and I forgot to mention, there will be relays between the switch and the power inputs to the fan controller, just did not add them for simplicity on the drawing. [img]images/graemlins/cool.gif[/img]
post #3 of (permalink) Old 09-12-2003, 10:16 PM
 
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Re: Fan Wiring Question w/ Indcators

Your circuit will work ...

The isolation diodes should have a PIV rating of at least 50V and a current capacity of 4 times the coil current.

The LED series resistor is used to limit current and its value will depend on the LED you use. A 660 ohm resistor will limit the LED current to around 20-21 mA which may not be bright enough in daylight. Don't forget to figure the required wattage rating of the limiting resistor.
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post #4 of (permalink) Old 09-12-2003, 10:58 PM
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Re: Fan Wiring Question w/ Indcators

Just get a 12v LED..
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post #5 of (permalink) Old 09-13-2003, 12:43 AM
thejunker
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Re: Fan Wiring Question w/ Indcators

Thanks Rockcrusher. The LED is rated at 5V, 20mA with a max of 5V, 80mA.

mach2_nh, I looked for a 12V led that flashed and was bright enough (greater than 4mcd), but could not find one. This 5V one seemed to meet my requirements, so as long as I can make it work this way, then no prob.
post #6 of (permalink) Old 09-13-2003, 08:13 AM
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Re: Fan Wiring Question w/ Indcators

I don't think so. I'd expect you still need power on the "Power" input to the controller when you are in manual. Usually the "Manual" input is jumpered to +12V (or ground depending on the design) but still requires power to the "Power" terminal.

You also show a rocker switch which are typically rated at around 15A. I'd expect you would need about 3 times that as shown with the power for the fan coming from the switch.

Personally, I like solid state and would use a transistor switching circuit for the LED rather than the relay if you are going to stick with the LED. I don't know that you would be able to see the LED with the top off in direct sunlight.
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post #7 of (permalink) Old 09-13-2003, 09:57 PM
 
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Re: Fan Wiring Question w/ Indcators

In addition to what has been said, your fan controller will probably need a ground wire and I think your Bosch relay will need the red led wired to the normally closed contact, not the normally open like you have. Your way the light will blink when the relay picks up because the contacts will go closed when your fan is running. I would run a red light instead of the flashing led. If it is not bright enough, then just get a higher wattage bulb. Just use a flasher type relay to run it instead of the Bosch. I am assuming your relay is just a normal on/off relay and not a flasher type.
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post #8 of (permalink) Old 09-14-2003, 02:44 AM
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Re: Fan Wiring Question w/ Indcators

</font><blockquote><font class="small">In reply to:</font><hr />
I don't think so. I'd expect you still need power on the "Power" input to the controller when you are in manual. Usually the "Manual" input is jumpered to +12V (or ground depending on the design) but still requires power to the "Power" terminal.

[/ QUOTE ]

Good point Taz, I may have to re-think that. Perhaps running it as an interupt to the fan motor itself, after the signal passes through the controller.

</font><blockquote><font class="small">In reply to:</font><hr />
You also show a rocker switch which are typically rated at around 15A. I'd expect you would need about 3 times that as shown with the power for the fan coming from the switch.

[/ QUOTE ]

No problem there. THere will be relays between my switch and the controller/12V.

</font><blockquote><font class="small">In reply to:</font><hr />
Personally, I like solid state and would use a transistor switching circuit for the LED rather than the relay if you are going to stick with the LED. I don't know that you would be able to see the LED with the top off in direct sunlight.


[/ QUOTE ]

I will be able to see it, it is an extremely bright LED, and I set it up in a hooded mount.



post #9 of (permalink) Old 09-14-2003, 02:51 AM
thejunker
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Re: Fan Wiring Question w/ Indcators

</font><blockquote><font class="small">In reply to:</font><hr />
In addition to what has been said, your fan controller will probably need a ground wire and I think your Bosch relay will need the red led wired to the normally closed contact, not the normally open like you have. Your way the light will blink when the relay picks up because the contacts will go closed when your fan is running. I would run a red light instead of the flashing led. If it is not bright enough, then just get a higher wattage bulb. Just use a flasher type relay to run it instead of the Bosch. I am assuming your relay is just a normal on/off relay and not a flasher type.

[/ QUOTE ]

Ya, the fan controller I drew is very simplified in comparison to the real one. A ground wire is in there in real life. (THe PDF link shows all the connections).

It is wired to the normally closed contact, so that when power is off to the fan (and thus the relay) , the blinking light is on. The other lamp, shows up when the fan is on. ( If I am mistaken on this, please let me know)

I chose the 5V flashing led, because it was cheaper than a 12V LED + a flasher relay. Maybe not by much, and the flasher way is probally easier, but its what I found, and I am only near a parts store once a month or so, I am hoping I can make it work with what I got.
post #10 of (permalink) Old 09-15-2003, 10:38 AM
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OT, the fan controller

I'm using this fan setup on my Jeep but didn't care for the supplied controller. My upper hose blew off twice when the vinyl tape got hot. I then installed the probe and gasket without the tape but not trusting the setup I overtightened the hose clamp and crushed the tube. Just a heads up on this, carry some extra water in case your hose comes off.

Gary
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