Anyone using the counter?

XRinger

XRinger

Member
I have this Radon detector, running 24/7 in my basement.
http://www.4radon.com/safety-siren-pro-series-3-radon-detector.html
 
"Audible Alarm: 85dB at 10cm - Beeps every hour if readings reach 4 pCi/L or greater."
(The alarm isn't really very loud, and can hardly be heard upstairs).
 
I was thinking about hacking the detector's beeper. I would attach an opto isolator chip
that would allow the beeping to increment the CAI counter.
 
Comments or suggestions please.
 
Thanks,
Rich
 
Actually have an old model too.
radonJune13_zps88f22d5c.jpg
 
XRinger said:
I have this Radon detector, running 24/7 in my basement.
http://www.4radon.com/safety-siren-pro-series-3-radon-detector.html
 
"Audible Alarm: 85dB at 10cm - Beeps every hour if readings reach 4 pCi/L or greater."
(The alarm isn't really very loud, and can hardly be heard upstairs).
 
I was thinking about hacking the detector's beeper. I would attach an opto isolator chip
that would allow the beeping to increment the CAI counter.
 
Comments or suggestions please.
 
Thanks,
Rich
Click to expand...
 
I'm using a counter for several things; anemometer input (low sped, up to a few KHz) and for my flux-gate magnetometer.
(The frequency measurement has too much drift and short-term variability, so sampling over a longer time and dividing is producing more useful results)
 
If your sensor beeps once per hour when the level is over a given value, are you just going to use the counter as a trigger/flag?
It'd be neat if you could count pulses from the ionization chamber so not only do you get a trigger, but can read the value!
 
rossw said:
I'm using a counter for several things; anemometer input (low sped, up to a few KHz) and for my flux-gate magnetometer.
(The frequency measurement has too much drift and short-term variability, so sampling over a longer time and dividing is producing more useful results)
 
If your sensor beeps once per hour when the level is over a given value, are you just going to use the counter as a trigger/flag?
It'd be neat if you could count pulses from the ionization chamber so not only do you get a trigger, but can read the value!
Click to expand...
 
Okay! 'anemometer input', seems like that would be easy. Good idea! I have one around here some wheres.  It just needs a magnet and a Hall-Effect.
Seems like the CAI is geared towards being a weather station.
 
 
If the level is 4 pCi/L or higher, the detector starts a one hour cycle, with 4 beeps every hour. So, when the program sees a count of 4 (or higher) in the counter,
it will send me an email, and perhaps turn on the basement fresh air blowers. So, it will just be a trigger-flag.
The only data needed, is when the level is above the 'safe'* level. 
*Safe per the government. I don't think there is any safe level for Radon, due to the long lasting by-products it generates as it decays.
 
The level tends to increase during the rainy season or during snow melts. Radon emissions are triggered by changes in the water table level.
So, it would be nice to be alerted if the problem gets serious. If it flags, I can just walk down and take a peak at the actual readings on both displays.
 
 
What are you using a flux-gate magnetometer for? Robotics?
 
Thanks,
Rich
 
would it be easier just to take hot wire going to beeper and put on TTL input?  As long as you use same ground there should be no problem with noise.
 
I have a setup on gas detector this way and workes great.
 
 
 
Tom
 
pittom said:
would it be easier just to take hot wire going to beeper and put on TTL input?  As long as you use same ground there should be no problem with noise.
 
I have a setup on gas detector this way and workes great.
 
 
 
Tom
Click to expand...
I was thinking about that, but I'm not even sure if the detector is using TTL levels (0 to +5V).
The detectors use 18Vdc 200mA wall-wart supplies.
 
I'm pretty sure that wiring up a simple Opto isolator will do the job. (I have all the parts needed).
I'll measure the voltage across the beeper, and select a resistor for the LED in the opto iso.
I assume that a 2.2k pull-up at the input of ip1 will be needed.  
 
The wire run will be about 30 feet, so I'll need to install a ferrite core and RF filtering on the cable into the CAI board.
We have a lot of local RFI, and I have Ham radio gear that might get used once in a while.
 
XRinger said:
Okay! 'anemometer input', seems like that would be easy. Good idea! I have one around here some wheres.  It just needs a magnet and a Hall-Effect.
Seems like the CAI is geared towards being a weather station.

 
What are you using a flux-gate magnetometer for? Robotics?
Click to expand...
 
I'm using a helicoid propvane - it's significantly more responsive than a conventional cup-type anemometer.
http://www.ambientweather.com/rry05103.html
 
The FGM is just something I'm playing with, hoping to gather more useful information on CME and GMS, polar drift etc.
I can't think of anything in robotics that would justify such a sensitive instrument!
 
XRinger said:
I'm pretty sure that wiring up a simple Opto isolator will do the job. (I have all the parts needed).

I'll measure the voltage across the beeper, and select a resistor for the LED in the opto iso.
I assume that a 2.2k pull-up at the input of ip1 will be needed.  
 
The wire run will be about 30 feet, so I'll need to install a ferrite core and RF filtering on the cable into the CAI board.
We have a lot of local RFI, and I have Ham radio gear that might get used once in a while.
Click to expand...
 
Instead of running the opto in the conventional "emitter-to-ground, open-collector-with-pullup" configuration, why not connect emitter to the WC input and collector to +5V? Then the existing pull-down resistors will work.
 
As for noise-reduction, think smarter, not harder. Run the "high signal level" wires from the detector to the WC board. Put the opto right at the WC.
You are unlikely to have enough noise induced in the high-level signal wires to cause a problem, and with short wires from the opto to the WC input you don't need all the extra filtering.
 
rossw said:
I'm using a helicoid propvane - it's significantly more responsive than a conventional cup-type anemometer.
http://www.ambientweather.com/rry05103.html
 
The FGM is just something I'm playing with, hoping to gather more useful information on CME and GMS, polar drift etc.
I can't think of anything in robotics that would justify such a sensitive instrument!
Click to expand...
I saw this:  http://whatis.techtarget.com/definition/fluxgate-magnetometer
and the idea of using a fixed magnetic field, for precision positioning seems like a pretty good way to use the technology.
Especially if you had a robot building products that were non-magnetic.. Like plastics.. :)
 
XRinger said:
I saw this:  http://whatis.techtarget.com/definition/fluxgate-magnetometer
and the idea of using a fixed magnetic field, for precision positioning seems like a pretty good way to use the technology.
Especially if you had a robot building products that were non-magnetic.. Like plastics.. :)
Click to expand...
 
I don't think it's good enough for what *I* would call "precision positioning".
Seriously though, you can think of mine as being like a "seismograph for magnetic fields". When we have an earthquake, seismographs around the world sense it and work out where and how big. FGMs can measure changes in the earths magnetic field caused by geomagnetic storms, coronial-mass-ejections from the sun and effects of the solar wind etc.
 
When I had it sitting in my office, someone moving a car 100 feet away produced a substantial shift in output. I also found out my office swivel-chair must have some residual magnetism, as swinging it produced massive changes in output from 10 feet away :)
 
rossw said:
Instead of running the opto in the conventional "emitter-to-ground, open-collector-with-pullup" configuration, why not connect emitter to the WC input and collector to +5V? Then the existing pull-down resistors will work.
 
As for noise-reduction, think smarter, not harder. Run the "high signal level" wires from the detector to the WC board. Put the opto right at the WC.
You are unlikely to have enough noise induced in the high-level signal wires to cause a problem, and with short wires from the opto to the WC input you don't need all the extra filtering.
Click to expand...
I prefer to use the grounded emitter because it keeps the line well loaded. No high impedance state, unless the pull-up resistance is too high.
Old school 7400 TTL guy, not a big fan of pull-downs.
 
I was considering making a little board with a few 4N35 chips, to hang under my CAI board, and run the beeper drive voltage back from the detector.
 
A ferrite core on the wire at the detector, may keep RFI from getting onto it's board.
 
pittom said:
is there a led that blinks when it beeps? 
Click to expand...
There may be one. It shows up during testing and reseting (a left-side LED segment of the display).
Not sure if it's flashing during a 4 pCi/L  event, since I've never watching when  the alarm sounded.
 
I started off with the idea of a non-invasive hack, but I want the signal to be super reliable, and since the warranty is over, there no need to preserve the seals. 
 
rossw said:
I don't think it's good enough for what *I* would call "precision positioning".
Seriously though, you can think of mine as being like a "seismograph for magnetic fields". When we have an earthquake, seismographs around the world sense it and work out where and how big. FGMs can measure changes in the earths magnetic field caused by geomagnetic storms, coronial-mass-ejections from the sun and effects of the solar wind etc.
 
When I had it sitting in my office, someone moving a car 100 feet away produced a substantial shift in output. I also found out my office swivel-chair must have some residual magnetism, as swinging it produced massive changes in output from 10 feet away :)
Click to expand...
That's pretty dang sensitive.
 
The old 1977 NEC Spinwriter printers used rotary Inductosyn transducers to position their print head and they were surprisingly accurate.
I think there might have been some linear inductosyn hardware used for positioning hard disk heads back in those days too..
 
 
Back in the mid 90s, I was a manufacturing test guy for NEC and we had a test line for analog computer monitors.
They were having a heck of a time with convergence adjustments. Monitors were changing convergence, as they moved down the test line.
I had a hunch and took a compass with me when I visited the factory. Large steel support members all around the test area.
All of them were very magnetic. I checked around and found there was a nearby research lab doing magnetic 'pulse' work. 
Not sure what they were doing, but the problem popped up so suddenly, it made me suspicious.
 
I had the factory guys move the work stations away from any heavy metal objects and things got back to normal. :)
 
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