another place for NTCs...*pics*

[FILIPPO]

I have found that is not so convenient to install an NTC in the tail cap of a mag this because of some reaseons i.e. you cannot put have some spare bulbs in the light and I have some trouble trying to disconnect the spring from the circuit.

so I decided to put it in the opposite part of the flashlight: near the switch.

this mod isn't difficult and allows you to carry bulbs in tail cap.
I have seen a pic of an NTC with a KIU socket but for my new light I decided to use a FM bi-pin to PR base adapter...

here some pics ( I cannot find some pic of them installed so I decided to post them).

you need to cut the negative contact of the standared switch to connect the NTC.

PS: thanks, jim for your present!

 

[jeffosborne]

Pardon my ignorance - what is an NTC? Jeff

 

[HammerSandwich]

An NTC offers resistance that decreases with temperature. In this use, it's a soft-start mechanism.

 

[2xTrinity]

An NTC offers resistance that decreases with temperature. In this use, it's a soft-start mechanism.

NTC is also an acronym for Negative Temperatre Coefficient.

An incandescent filament on the other hand acts as a PTC, or positive temperature coefficient resistance -- it has a very low resistance when cold, high resistance when up and running. That means if you switch an incan directly to a battery, there will be a big "spike" of current, this could create problems for batteries with protection circuit, and simply put additional wear and tear on the lamp filament and switch. By adding a NTC, this inrush current is eliminated.

The disadvantage is that even when fully warmed up, there is still some resistance, and consequently power loss, in the NTC. A PWM soft starter on the other hand has neither of these problems -- that uses big transistors to rapidly "switch" the current off and on so quickly that it behaves like a lower steady current. PWM in the case of incans can be used to provide regulation, or run say a 6V lamp off of a 12 battery by feeding the lamp current at a reduced duty cycle.

 

[missionaryman]

Great thinking Flippo - does the NTC melt the plastic when it get's hot?

 

[FILIPPO]

Great thinking Flippo - does the NTC melt the plastic when it get's hot?

I haven't tested it yet ...

I'm still waiting for my mag 1,5D and iys battery pack.

anyway I think it's difficult to melt the plastic switch.

before doing that I was running NTC in my mag85 (3D but with KIU socket) in the tail cap and I used to isolate wires with tape near the NTC ant it didn't melt :thumbsup:

IMO a NTC can get hot but not too much...