hedgerow is going techno AGAIN, gawd help us

[hedgerow pete]

ok pips, i have just had a great idea about redesigning the hendron collider.

i have at home a 12v dc polystyrene egg incubator which has a 1.25amp power supply that in turns runs a 12 volt dc 10 watt halagen bulb as the heating source, i am sure you have seen what i am on about on fleabay and the like. the box its self has a rough area inside of 1 cubic foot.

still with me?

now i want to use a slightly large polystyrene box with the same control/bulb set up but this box is 2 cubic foot?

here goes the techno gribberish!!

i was going to simply increase the light bulb power to either , 20 watt, 30 watt or 35 watt or even 50 watts all still at 12 volts dc.

following?

the relay that the bulb is wired into is rated at 10 amps at 28 volts dc so i should be ok , but will i have to increase the power supply to the relay, i have avalible to me the following, but where i am lost is trying to work out my mA,Va,Amps and watts, and i am not getting any sence from either of my brain cells tonight.

so power supplies avalible are,

10 volts dc 1.5amp
12 volt dc 1.25 Amp
12 volt dc 90 Va
12 volt dc 4.5amp
12 volt dc 3500mA

or the one i am now using which is 12 volt dc. 1.25 amp.

so back to you techno guys,

what power light bulb to use, (its on an auto turn on and off thingy)???
and what power supply to use ????

 

[Bee-Key-Pur]

I this for hatching chicks, it might be a tad over the top. But I like the way you think. Keep up the good work...

Brian

 

[SER]

Not sure about which size bulb will be enough but to work out power supplies you can use the following,

Power= amps*volts

So a 20w bulb at 12v is

I = 20/12
I = 1.6 amps

So at 12 volts

20w bulb = 1.6 amps
30w bulb = 2.5 amps
35w bulb = 2.9 amps
50w bulb = 4.2 amps

 

[hedgerow pete]

thanks ser that does help

 

[Hombre]

As SER has said basically, but presented differently.

I understand that the Power Supply Unit (PSU) is rated at 12V 1.25A = 15W
The relay coil is obviously 12V and shouldn't take too much in the way of current, so no change there..

The relay contacts are rated at 28V 10A (280W but of no consequence) The voltage rating is conservative and the current is in-bounds, so should be good. For switching up to a 50W bulb, but your PSU is only good for 15W and will be at the edge of it's stated performance rating at 15W, depending on how conservatively that it has been rated by he manufacturer.

12V 1.25A = 15W is just about good for a 15W bulb, but has little headroom. Good for 10W.
12V 3.5A (3500mA) = 42W is good for up to a 40W bulb.
12V 4.5A = 54W is good for up to a 50W bulb.
12V 90VA = 7.5A is good for up to a 80W bulb.

Your Relay is good to go.
Your PSU may be too small for extended reliable operation on 15W.

I doubt that it will take twice the power to maintain the temperature in twice the volume, so would think of going to a 15W bulb with your current PSU.

You don't say if the unit is thermostatically controlled? If it is, then a 20W bulb (or 2 x10W) is probably the better option being on less of the time and a 3.5A PSU is good. Obviously a 15W bulb could by used as a spare.

Are details available on line for a look see at the spec of the unit you have?

 

[hedgerow pete]

no they are not on line that i can find. what i am thinking of doing is using this power supply unit i have found from another item at home

http://www.maplin.co.uk/worldwide-ac-dc-multi-voltage-3600ma-power-supply-48908

i belive it will supply me 3.6amps which will easily cover the ampage needed for a 20 watt or even 30 watt bulb if needed.

i like the simple idea of throwing in a 20 watt bulb and seeing if thats ok for now. i will let you know how i get on, thanks all for the advice

 

[picton farm]

Look for a second hand corti incubator with a fan. They work and cost less than £100 new so second hand should be very cheep!

 

[victor meldrew]

ok pips, i have just had a great idea about redesigning the hendron collider.

i have at home a 12v dc polystyrene egg incubator which has a 1.25amp power supply that in turns runs a 12 volt dc 10 watt halagen bulb as the heating source, i am sure you have seen what i am on about on fleabay and the like. the box its self has a rough area inside of 1 cubic foot.

still with me?

now i want to use a slightly large polystyrene box with the same control/bulb set up but this box is 2 cubic foot?

here goes the techno gribberish!!

i was going to simply increase the light bulb power to either , 20 watt, 30 watt or 35 watt or even 50 watts all still at 12 volts dc.

following?

the relay that the bulb is wired into is rated at 10 amps at 28 volts dc so i should be ok , but will i have to increase the power supply to the relay, i have avalible to me the following, but where i am lost is trying to work out my mA,Va,Amps and watts, and i am not getting any sence from either of my brain cells tonight.

so power supplies avalible are,

10 volts dc 1.5amp
12 volt dc 1.25 Amp
12 volt dc 90 Va
12 volt dc 4.5amp
12 volt dc 3500mA

or the one i am now using which is 12 volt dc. 1.25 amp.

so back to you techno guys,

what power light bulb to use, (its on an auto turn on and off thingy)???
and what power supply to use ????

4.5 amp is the one it should give you 2.4 amps to spare in case the 10 watt jobby is insufficient .( 2 more 10 watt lamps in fact )

John Wilkinson

 

[hedgerow pete]

we got the 4 amp power supply and needed it as we have had to use the 30 watt bulb to get the temp stable enough, the ten was not strong enough and the 20 was just short of the 37.5 i wanted so in went the 30 watt.

i realise that polystrene boxes and cheep electronics is not the way to go with hatching eggs but i was using a brinsea untill its owner wanted it back and thats why the sudden shake up. we are not fussed if we hatch or not as the eggs are very out of season in january and february and as a novice i am bound to make many mistakes.

i must admit after bodging the plastic one together yesterday i suddenly realised how easy they are to make.

so we are now looking for a new machine for next months eggs. i liked the brinsea 20 we were using as it was fully auto but its way past the pocket money at the moment, there are several others avalible but most second hand ones are non turning so i might end up with one of those instead.

thanks for the tips all

 

[hedgerow pete]

just incase anyone is interested i can upload the photos of the set up of the control unit so you can copy it yourself?

 

[hedgerow pete]

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