Biltong box - need to power a 100W bulb and a 12V fan

[winston1]

I was thinking of using a LED Driver Power Supply Transformer 240V - DC 12V to power the PC fan

You'll probably find that the LED Driver needs a minimum current to work properly, and that minimum current is more that the demand from the fan - and this will mean the LED Driver can't regulate the voltage properly. Take a look at the current rating of the fan, and report back.

Nozzle

This is the one i had in mind. I'm not sure of the fan rating (except it's a 12V fan), but i can see that the converter is min 0.5W, which is only about 42mA.
http://tinyurl.com/n5qdoda

.[/quote
I can't see anything about a minimum load on that listing.

 

[winston1]

thanks

Is there a component i can buy to split off the mains lead?

Is this serious. Two way adapters are readily available in any supermarket, or pound shop.

 

[bernardgreen]

Repeat

Running a 12 volt fan from a LED driver is un-likely to be successful.

The "12 volt" supply is likely to be a pulsed output with an average voltage of 12 volts. LEds can cope with such pulsed supply. a fan may not cope well.

 

[frustin]

thanks

Is there a component i can buy to split off the mains lead?

Is this serious. Two way adapters are readily available in any supermarket, or pound shop.

winston1, I appreciate that you're responding to my thread, but the only thing you've done is criticise so far and even one of those was wrong.

I would like to use one mains cable for my box. It must power the lamp and the fan (however this can be done). I dont want to run two mains cables, when I can run both from a single one. I'm asking how I can safely but cheaply do that.

 

[Nozzle]

Just any-old junction box, or "daisy-chain" the connections on the power supply. (i.e. two wires into each terminal; one cable from the mains, the other to the 100W lamp)

Nozzle

 

[frustin]

Repeat

Running a 12 volt fan from a LED driver is un-likely to be successful.

The "12 volt" supply is likely to be a pulsed output with an average voltage of 12 volts. LEds can cope with such pulsed supply. a fan may not cope well.

any ideas? computer psu can deliver the 12v but that's overkill and i'd need another plug socket.

 

[Nozzle]

You could try an electrolytic capacitor in there to smooth out the peaks (watch out for polarity), or nick a mains adaptor from some other gadget. I don't think the peaks will be excessive enough to damage.

The capacitor idea wont work if the power supply has negative-going peaks (troughs..)

Nozzle

 

[winston1]

thanks

Is there a component i can buy to split off the mains lead?

Is this serious. Two way adapters are readily available in any supermarket, or pound shop.

winston1, I appreciate that you're responding to my thread, but the only thing you've done is criticise so far and even one of those was wrong.

I would like to use one mains cable for my box. It must power the lamp and the fan (however this can be done). I dont want to run two mains cables, when I can run both from a single one. I'm asking how I can safely but cheaply do that.

Do you want help or not? To be honest, and here is a genuine critism, the sort of questions you have been asking implies you are not competent for this task and shoud employ a qualified professional.

 

[winston1]

You could try an electrolytic capacitor in there to smooth out the peaks (watch out for polarity), or nick a mains adaptor from some other gadget. I don't think the peaks will be excessive enough to damage.

The capacitor idea wont work if the power supply has negative-going peaks (troughs..)

Nozzle

If it is a pulsed output the electrolytic will charge to peak value, whatever that is, and likely over run the fan.

 

[JohnW2]

Repeat Running a 12 volt fan from a LED driver is un-likely to be successful. The "12 volt" supply is likely to be a pulsed output with an average voltage of 12 volts. LEds can cope with such pulsed supply. a fan may not cope well.

That may be true of some LED drivers, but I have to say that I routinely use cheap "12V DC Led Drivers" for mains-driven control of standard 12V plug-in relays (120Ω, 100mA, 1.2W), without any trouble, and the DC output of the 'driver' is remarkably clean (this is an Aurora 12V 0.8A constant-voltage LED driver, loaded by 1 relay such as I described). Apologies for grotty photo, but I think it illustrates the point!:

Untitled

• JohnW2
• 9 Jun 2014
• 2

I'm sure that would happily power a small 12V DC fan.

Kind Regards, John

 

[ban-all-sheds]

This whole project seems beset by a combination of insufficient knowledge, insufficient thought, insufficient research, and an apparent desire to overcomplicate and use inappropriate components. An LED driver for a fan?

A light bulb for heating?

What on earth is wrong with using a 230V 100W enclosure fan heater?

 

[JohnW2]

You could try an electrolytic capacitor in there to smooth out the peaks (watch out for polarity)...

If you did have a driver (such as bernard described) with a 'messy' output, then you might well not even need an electrolytic capacitor - if it' a SMPSU, the frequency could well be high enough for a modest size (non-electrolytic) capacitor to be adequate. Having said that, if the one I recently illustrated is anything to go by, the manufacturers have probably already thought of that, and already include an adequate capacitor (and/or other regulation circuitry) in the driver to produce a pretty clean DC output.

Kind Regards, John

 

[frustin]

This whole project seems beset by a combination of insufficient knowledge, insufficient thought, insufficient research, and an apparent desire to overcomplicate and use inappropriate components. An LED driver for a fan?

A light bulb for heating?

What on earth is wrong with using a 230V 100W enclosure fan heater?

The light bulb (located at the bottom) for the box, which measures 900x500x400, is supposed to heat the internal area to roughly 60degsC. The moisture, from the drying meat, is sucked out of the top by the fan.

 

[winston1]

This whole project seems beset by a combination of insufficient knowledge, insufficient thought, insufficient research, and an apparent desire to overcomplicate and use inappropriate components. An LED driver for a fan?

A light bulb for heating?

What on earth is wrong with using a 230V 100W enclosure fan heater?

The light bulb (located at the bottom) for the box, which measures 900x500x400, is supposed to heat the internal area to roughly 60degsC. The moisture, from the drying meat, is sucked out of the top by the fan.

In that case an LED driver in the box will fail quickly. They are not designed to run in an ambient temperature of 60C.

 

[JohnW2]

The light bulb (located at the bottom) for the box, which measures 900x500x400, is supposed to heat the internal area to roughly 60degsC. The moisture, from the drying meat, is sucked out of the top by the fan.

BAS is undoubtedly right in saying that the same could be achieved, 'more simply', just by using a 230V 100W enclosure fan heater - located near the bottom, with a vent at the top (as well as the 'input vent' at the bottom, for the heater) for it to 'push' the moist air out. However, where I seemingly differ from BAS is that I have no problem with 'improvisation', such as you propose, so long as it is done satisfactorily.

However, don't forget that, even with your proposed system, you'll need an input vent, probably somewhere near the bottom. If 'new air' can't be 'sucked in', the fan at the top will not be able to blow anything out.

Kind Regards, John