Verification that Heated Pitot is working

Find one of those out door thermometers with a remote read out. Some
of the older ones had a meter. The newer ones have a battery powered
digital read out which could probably be adapted to the plane's
electrical system, but you wanted simple.


KISS, the best approach........

It will even tell you if the heater is not up to the job regardless of it's
on or off state.

Peter

system and the heating element draws 7 amps. I know I can not use a
LED in series because it would blow the milli-second I turned the unit
on. I know I can't use a light or lamp in parallel because it would
not indicate if the heated pitot was on or off. So that is my dilemma.

You should be all set if you put an LED in parallel with a resistor
in series with the heater. Basically you're making a high-current
ammeter. The values of the LED and resistor depend most on what's
available at your local Radio Shack or equivalent.

Find one of those out door thermometers with a remote read out.

You'd mount that out on the pitot tube?! That seems a bit extreme.

--kyler

On Fri, 21 Oct 2005 14:17:02 GMT, Kyler Laird
wrote:

system and the heating element draws 7 amps. I know I can not use a
LED in series because it would blow the milli-second I turned the unit
on. I know I can't use a light or lamp in parallel because it would
not indicate if the heated pitot was on or off. So that is my dilemma.

You should be all set if you put an LED in parallel with a resistor
in series with the heater. Basically you're making a high-current
ammeter. The values of the LED and resistor depend most on what's
available at your local Radio Shack or equivalent.

Find one of those out door thermometers with a remote read out.

You'd mount that out on the pitot tube?! That seems a bit extreme.

Inserting a second wire into the assembly is extreme? In addition it
lets you know how well the system is working, particularly if it's one
of those two heater types.

The Deb has a digital read out for a number of parameters (Includes
temp in F and C, Density altitude, battery voltage, etc...). All I'd
need to do with something like that would be hook up the TC leads.

Any time I'm in rain, or visible moisture the pitot heat is on.

BTW, I've flown loose formation to Oshkosh with a Cozy a number of
times. One day there were scattered showers all along the path. I
thought I was going to wear out the vernier throttle on the Deb trying
to stay in position.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

--kyler

iflycozy wrote:
Question to you electrical designer gurus:

Here is what I would like to do and Jim Wier suggested that I post this
here. I want an indicator on my Cozy homebuilt airplane to show me
that my heated pitot is actually working when I turn on the switch on
the instrument panel. So, the light will go out (with the switch still
in the on position) if the heated pitot stops working for some reasons
(but not because it tripped the circuit breaker). So, how can I build
such a device or circuit? I would appreciate specific parts or
identification of parts as I am an amateur. This is a 12 volt DC
system and the heating element draws 7 amps. I know I can not use a
LED in series because it would blow the milli-second I turned the unit
on. I know I can't use a light or lamp in parallel because it would
not indicate if the heated pitot was on or off. So that is my dilemma.
Please help.

Reply to:




I would use an ammeter as the most simple solution.

If you must have a light, it must be something that senses current
because current is what generates the heat, and you want an indication
if your heated pitot is working.

There are some simple circuits that would allow you to turn on a light
when current is flowing in a circuit. You will need to put a sense
resistor in the circuit.

Another simple way is to put in a miniature panel ammeter so you can
actually see the current used. I got one of them (real tiny) for my
inflight adjustable IVO prop so I can tell when it is at extremes. More
info on the tiny panel ammeter at http://www.abri.com/sq2000/hints.html
Would be a much simpler circuit and probably safer.

iflycozy wrote:
Question to you electrical designer gurus:

Here is what I would like to do and Jim Wier suggested that I post this
here. I want an indicator on my Cozy homebuilt airplane to show me
that my heated pitot is actually working when I turn on the switch on
the instrument panel. So, the light will go out (with the switch still
in the on position) if the heated pitot stops working for some reasons
(but not because it tripped the circuit breaker). So, how can I build
such a device or circuit? I would appreciate specific parts or
identification of parts as I am an amateur. This is a 12 volt DC
system and the heating element draws 7 amps. I know I can not use a
LED in series because it would blow the milli-second I turned the unit
on. I know I can't use a light or lamp in parallel because it would
not indicate if the heated pitot was on or off. So that is my dilemma.
Please help.

Reply to: