The pandemic introduced with it a necessity to keep up sufficient air flow in enclosed areas, and thus, there’s been appreciable curiosity in cheap C02 screens. Sadly, there are unscrupulous actors on the market which have seen this as an opportunity to make a fast revenue.

Just lately [bigclivedotcom] received one such low-cost CO2 sensor on his bench for a teardown, and confirms that it’s a pretend. However in doing so he reveals an interesting story of design selections good and unhealthy, from one thing which might virtually have been a helpful product.

Behind the slick shade show is a PCB with an unidentified microcontroller, energy provide circuitry, a DHT11 environmental sensor, and an extra small module which purports to be the CO2 sensor. He rapidly demonstrates with a SodaStream that it doesn’t reply to CO2 in any respect, and thru additional exams is ready to establish it as an alcohol sensor.

Past the alcohol sensor he analyses the PSU circuitry. It has a spot for a battery safety chip but it surely’s not fitted, and an error within the regulator circuitry results in a sluggish drain of the unprotected cell. Most oddly there’s a complete 5 volt switching regulator circuit that’s fitted however unused, being in place to assist a lacking infra-red module. Lastly the display screen is an application-specific LCD half.

It’s clear some effort went in to the design of this unit, and we are able to’t assist questioning whether or not it might have began life as a design for a higher-spec real unit. However as [Clive] says, it’s a celebration detector, and of little extra use than as a mission case and battery.

Want extra doubtful instrumentation? How a couple of magnetic area tester?