On Thu, Nov 10, 2022 at 12:36 AM, Kelly wrote:
in the sensors you have implemented have you used a 1K resistor like this with good success across most readings
In short yes, but it wasn't for any radio related project.
I setup a "room monitor" for a friend doing sleep studies.? He wanted an inexpensive "box" to collect room data during a few nights during which the subject gave information about how they slept.? The idea was a kind of a pre-check of environmental stuff before bring them in for a real sleep study.
I used 1k resistor with the CdS cell, but changed to 10K because the project was not intended to be used in bright daylight (room at night).
With 1k, I got 10-bit ADC values of 15 to 515 bits.? Changed to 10k and got 130 to 930 bits for the range I needed to measure.
The project had a RTC (I2C), ambient light sensor (CdS resistive), Temperature (TMP37), condenser Mic with supporting components, and an SD card to hold the data.
The Mic data was 'kind of peak sampled' and pseudo averaged over a second before storing - kind of cool idea, but won't get into that here.
To do this directly with a MTT4B on J3 (pin1 Vcc to pin7 R15), I would probably go with something like this:
? ?Pin 2 ---------------------------------------------------------------------------------- Vcc
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? |? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? |? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? |? ? ?
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? |? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?Rt? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? |
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?CdS? ? ? ? ? ? ? ? ? ? ? 6------|? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? Mic---------- additional Mic circuit ------ 5? ??
? ? ? ? ? ? ? ? ? ? ? 7 -------|? ? ? ? ? ? ? ? ? ? ? ? ? ? ? TMP37? ? ? ? ? ? ? ? ? ? ? ? ? ??|
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?Rl??? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?|? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?Rs? ? ?
? ?Pin 1 ---------------------------------------------------------------------------------- Gnd
Note:? Pin 7 (I believe) is JP5 of the TT4 and would be reported after TeleVolt, and TeleTemp.?
? ? ? ? ? ?Or the start of the telemetry data if those are OFF.?
In my project:
? ? ? ? ? Resistors Rl (light), Rt (Temp), and Rs (sound) were kind of current limiting protection (separate for each).
? ? ? ? ? The sensors were mounted on a piece of perf board with a cable going to the Mico board.
? ? ? ? ? That was so they could be 'aimed' to not be at a window, or noise source.
FYI, I actually used the tutorial from Adafruit as my guide for the CdS sensor:??
Fixed BAD ERROR => Pin 2 is Vcc and Pin 1 is ground on J3 of MTT4B
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Rob KB8RCO
