Busscom Intercom - Changing power source - WILL THIS WORK

[Koevoet]

Busscom intercom is powered with a 9v battery - need to take off dash board to replace (banana pot)

Couple days back - 90 min flight - wind starting to pickup and that battery desided its time.

Had a young passenger with dead intercom - about 5min from landing - culprit battery.

Complained at electronic shop and they gave me 3 item with a diagram how to solder it - cost R10 bucks

This is the end result fitted on curcuit board - testing it at this stage on my car battery.

Changes 12v to 9v - Gives me a constant 8.85v - 8.50v (need 9v)

My question is - will it work without damaging my system - gatvol for battery.

[ZULU1]

Yes it will, thats a LM7809 in a TO220 package, fixed voltage regulator. They are rated at up to 36 Volts depending on brand and 1 amp continuous. They do however have a two volt drop out differential. However you will need some form of line choke and input capacitance and so on (Google part number for ideas on drawing layout) to prevent engine whine and so on entering the intercom circuit. This may be wire wound or some form of ferrite thats off the shelf. Try Mantech electronics in major centres as they stock some very good two conductor ferrites on the same core that work well.

Me I still prefer batteries, they have clean power and hassle free from the mains, just buy a nice Li Ion or Alkaline unit and thats more than adequate..

Happy New Year

Zulu1

[Duck Rogers]

Looks like a LM 7809 Voltage Regulator. Should give you constant 9v or so and should be able to handle up to 1 AMP current. Should be ok. I don't think that intercom draws more than 1amp.
I'm no expert, rather ask Zulu1

[Koevoet]

Thax guys -
I had to ask before i bugger up my system.

Zulu - i agree batt is much better but that fail factor,mmmm.

Think i must keep the batt and put the power supply in, with a 2 way toggle switch - if the power fail can swich to batt power.

Think thats gona solve the problem.

[Biggles]

Something else to consider is if you don't have a battery and you have an engine out you also won't have an intercom (with a fairly worried pax). If you have both you are double covered.

[Koevoet]

Biggles - very good point - gona rig it both ways.

Thax guys

[Tailspin]

Something else to consider is if you don't have a battery and you have an engine out you also won't have an intercom (with a fairly worried pax). If you have both you are double covered.

Why do you not put a recharable battery in and then have the external power charge the battery and if your motor does quit then your battery would at least have had some juice over till you are on the ground.

[Koevoet]

Also a good idee - Tailspin

[Ian]

Zulu1 , what about 3 LEDs (Green, orange, red) with the right zener's etc and a little push button.

At pre flight - push button, if Green - great , if Orange - battery going (experience would soon give the anticipated life left) , if Red - talk fast...

Weight is minimal and no connections to aerie (no increased risk of things to go wrong)

Happy new year !

ian