CO Detector modification

[Tasmag]

Hi there

 

I am hoping someone with better electronic knowledge than me can assist with a modification I would like to make to a CO detector I purchased recently.

 

I have been using a standard Caravan unit adapted to take aircraft power instead of batteries, but I want to change to a smaller unit I have.

 

The problem is that it does not turn on when power is applied to the charging input. (it was a shot in the dark hoping it would)

 

I don't need the battery, would be happy if it turned on when power is applied and off when not. (Possibly even better that way as the sensor might last longer)

 

Any ideas on a simple way to achieve this.

 

[Blueadventures]

Might be best to retain the on / off switch method; as that will allow turning on before you turn on master so it can calibrate.  

[Tasmag]

It seems like the only calibration is a 3 minute warm-up time, as best I can work out anyway.

[RFguy]

how do you usually turn it on ?

[Tasmag]

Long press on the top to turn on or off, short press turns off the screen but keeps the detector running. 

 

Right-hand switch in the internal pic as you look at it.

 

The other 3 change °C/F, Voice alarm on/off and Chinese/English voice

 

Mike

[RFguy]

on the switch

is one side of the switch at ground , or battery , or neither ? detemrine with a multimeter

 

what we need to do is put a small circuit in there to generate a contact closure on power up

 

If you push the ON button as the power is applied, and hold for 5 seconds, does it turn on ?

Or do you have to plug in, wait x seconds, then hold the power button down ?

 

 

 

[RFguy]

also, it might not function correctly without th ebattery installed- the battery might need to stay, so we also generate a power off closure on power down.

 

[Tasmag]

RFguy

 

Thanks for the replies.

 

For the life of me, I cant find my multimeter to check the switch grounding.

 

I will get back to you as soon as I find it.

 

Based on the Circuit board I would say it is switching to ground though.

 

Mike

[Tasmag]

I have found the multimeter. (As soon as I gave up looking for it!)

 

The switches all switch to ground, but interestingly the red and black wires from the battery to the board are around the wrong way. 

 

And it does not turn on if you hold the switch and apply power.

 

Mike

 

 

[Tasmag]

Thinking in what you said earlier about a circuit to initiate the start, what about this as the 5 second pulse to turn on. 

 

Remove the battery and it will turn off itself. I could leave the battery in but it makes a racket when it goes flat. 

 

Mike

 

 

AU$4.54 | DC 5V 12V 24V Dual Adjustable Cycle Timer Dual Delay On/Off Switch 0-100 Seconds 0-15 Minutes Timer Control Delay Relay Module
https://a.aliexpress.com/_mMbe22a

 

Edited May 7 by Tasmag

[skippydiesel]

Maaat! I don't know about your CO detector - mines a Caravan/Marine type,  Velcro mounted in the cockpit, with its own batteries, that last for at least two years if not more. Has a nice big digital display, memory/history, so you can check back for Max CO ppm & light/sound alarm, stays on 24/7 - leave it with its batteries soooooooo simple!😈

[Freizeitpilot]

Because I have a 12v outlet, but needed a USB outlet, I splashed out and bought this.

 

https://www.flightstore.com.au/design4pilots-pilot-co-charger

 

Doesnt appear to be any method to check calibration, but my thinking was that it was better than nothing for CO detection.

[Tasmag]

46 minutes ago, skippydiesel said:

Maaat! I don't know about your CO detector - mines a Caravan/Marine type,  Velcro mounted in the cockpit, with its own batteries, that last for at least two years if not more. Has a nice big digital display, memory/history, so you can check back for Max CO ppm & light/sound alarm, stays on 24/7 - leave it with its batteries soooooooo simple!😈

Yep, thats pretty much what I had. Never been one to stop at simple though!

[Tasmag]

9 minutes ago, Freizeitpilot said:

Because I have a 12v outlet, but needed a USB outlet, I splashed out and bought this.

 

https://www.flightstore.com.au/design4pilots-pilot-co-charger

 

Doesnt appear to be any method to check calibration, but my thinking was that it was better than nothing for CO detection.

Freizepilot

 

I like that, wish i had seen it sooner actually. 

 

Mike

[skippydiesel]

$31-$40 DEPENDING ON WHERE YOU PURCHASE

[Tasmag]

19 minutes ago, skippydiesel said:

$31-$40 DEPENDING ON WHERE YOU PURCHASE

Thanks Skippy,

 

I like the combination of co and humidity on the one i purchased. I have plenty of temp sensors, but no humidity. 

 

I like to know the humidity for the carb icing predictions. 

 

Mike

[skippydiesel]

Carb ice in a Rotax 912?- flew my last Rotax powered aircraft for about 10 years. Cone filters (no airbox or carb heat) and never knowingly had icing. Under cowl temperatures a fairly consistent 10 C above ambient.

 

New aircraft with Rotax 912ULS with homemade/designed air box AND liquid anti ice/heated collar. So far about 8 months flying - no ice - under cowl temps around 25 C above ambient.

[skippydiesel]

Random thought:

It seems to me that it is better to always assume there is a risk of icing and instigate the preventative actions as a matter of course eg On aircraft fitted with carburettor heat, always switch to carby heat before reducing power for decent and or landing. By adopting this habit you  lose nothing and may prevent icing, when your carburettor is at its most vulnerable, low power setting.

[RFguy]

so, you'll need to solder up a few wires.

battery will probably need to stay. 

older ones are heater/catalyst type, they have lifespan

the way these systems get LONG  lifespan is they usually only sample a few times per hour.

I have a CO2 monitor that has a lifespan of 500 hours and provides twice a minute updates.

Newer sensors are either micro versions of same with long life sensors, or photometry type that measure absorption spectra.

I wonder which type this is.

 

[Tasmag]

Is there a way to tell the type of sensor, given that it has a 3 minute warm up i suspect an older type.

[Thruster88]

I tested mine in the garage with the roller door open, started the ride on, 100ppm after one minute.  Started giving a reading as soon as i could smell exhaust.  

Edited May 8 by Thruster88

[RFguy]

given that the atmospheric CO2 concentration is about 400ppm, I'm guessing it is displaying concentration above 400ppm. 

or a complete BS reading....

 

still, an increasing number is all that's really required. there should be no CO2 in the cabin.

 

Newer sensors are instant on. but the sensors, even wholesale in large quantity are USD$12-20, which isnt going to sell at BWS for less than $100 for that sort.

[Freizeitpilot]

Carbon monoxide or Carbon dioxide ?

[RFguy]

CO2 sorry got mixed up

LOL. I'm tired.

 

[RFguy]

So, something to keep in mind. Most of the "CO" sensors  at the low end are actually "air quality monitoring " sensors

CO is just one of the detected gases....

 

you need to spend more money to get a pure gas sensor. but of course there shoul;d be only air in your cabin.

cheap one - dual gas 

https://www.winsen-sensor.com/sensors/mems-gas-sensor/gm702b.html

https://www.winsen-sensor.com/product/gm-702b.html

 

for the new solid polymer sensors

https://www.sgxsensortech.com/solid-polymer-sensors

 

Here is an affordable one  USD15

https://www.sgxsensortech.com/sensor/mics-4514

https://www.sgxsensortech.com/uploads/f_note/0278_Datasheet-MiCS-4514-rev-16.pdf

 

amongst

https://www.winsen-sensor.com/co-sensor/