Karaburan - Revision history

Bertrik Sikken: /* Cheap non-bluetooth EC/TDS */

2026-06-08T09:06:52Z

Cheap non-bluetooth EC/TDS

← Older revision		Revision as of 09:06, 8 June 2026
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	The cheapie probably underestimates the EC, because its temperature reading is too high.		The cheapie probably underestimates the EC, because its temperature reading is too high.
	A temperature error of about 5 degrees means an error of about 10 percent.		A temperature error of about 5 degrees means an error of about 10 percent.

			Approximately +2% per °C increase in temperature (around room temperature).

	== Boat control ==		== Boat control ==

2026-06-06T18:43:49Z

Cheap non-bluetooth EC/TDS

← Older revision		Revision as of 18:43, 6 June 2026
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	Tear-down on hackaday: https://hackaday.io/project/184764-ectds-temp-meter-teardown		Tear-down on hackaday: https://hackaday.io/project/184764-ectds-temp-meter-teardown
			More info: https://dankar.github.io/hydrowatch/2014/11/20/interfacing-a-cheap-tds-meter-with-micro-controller/

	Comparison with the BT785, using tap water:		Comparison with the BT785, using tap water:

2026-06-06T14:51:56Z

Cheap non-bluetooth EC/TDS

← Older revision		Revision as of 14:51, 6 June 2026
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	* BT785: EC = 706 us/cm2, temperature = 20.7		* BT785: EC = 706 us/cm2, temperature = 20.7
	* cheapie: EC = 482 us/cm2, temperature = 24.2		* cheapie: EC = 482 us/cm2, temperature = 24.2

			The cheapie probably underestimates the EC, because its temperature reading is too high.
			A temperature error of about 5 degrees means an error of about 10 percent.

	== Boat control ==		== Boat control ==

2026-06-06T14:39:33Z

Cheap non-bluetooth EC/TDS

← Older revision		Revision as of 14:39, 6 June 2026
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	Tear-down on hackaday: https://hackaday.io/project/184764-ectds-temp-meter-teardown		Tear-down on hackaday: https://hackaday.io/project/184764-ectds-temp-meter-teardown

			Comparison with the BT785, using tap water:
			* BT785: EC = 706 us/cm2, temperature = 20.7
			* cheapie: EC = 482 us/cm2, temperature = 24.2

	== Boat control ==		== Boat control ==

2026-05-11T12:13:17Z

BT785

← Older revision		Revision as of 12:13, 11 May 2026
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	https://developer.tuya.com/en/docs/iot/tuya-cloud-universal-serial-port-access-protocol?id=K9hhi0xxtn9cb		https://developer.tuya.com/en/docs/iot/tuya-cloud-universal-serial-port-access-protocol?id=K9hhi0xxtn9cb

			More information on this wiki: https://revspace.nl/BT785
	Code: https://github.com/bertrik/bt785		Code: https://github.com/bertrik/bt785

2026-05-11T12:12:36Z

BT785

← Older revision		Revision as of 12:12, 11 May 2026
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	Does NOT speak the universal serialport access protocol as described here:		Does NOT speak the universal serialport access protocol as described here:
	https://developer.tuya.com/en/docs/iot/tuya-cloud-universal-serial-port-access-protocol?id=K9hhi0xxtn9cb		https://developer.tuya.com/en/docs/iot/tuya-cloud-universal-serial-port-access-protocol?id=K9hhi0xxtn9cb

			Code: https://github.com/bertrik/bt785

	==== Cheap non-bluetooth EC/TDS ====		==== Cheap non-bluetooth EC/TDS ====

2026-05-11T12:11:30Z

@@ Line 238: / Line 238: @@
 === Water measurement probes ===
 * https://nl.aliexpress.com/item/1005003784454381.html BLE-9908 Inexpensie "Yieryi" PH/EC/Temp probe with bluetooth and app, about E25,- (Uses 3x LR44 coin cell batteries)
 * Several different models: https://nl.aliexpress.com/item/1005007810989801.html
@@ Line 261: / Line 254: @@
 * pH sensors are almost by definition fragile and last only a limited time, so probably don't bother trying to use one at all. The pH of outdoor water might not be that interesting to measure.
 * I expect the non-TuYa meters to use an easier to handle bluetooth protocol, avoiding the need for complicated encryption with a key that can only be fetched for a limited time using a tuya developer account.
 == Boat control ==

2026-02-07T21:47:40Z

Water measurement probes

← Older revision		Revision as of 21:47, 7 February 2026
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	* EC is temperature dependent, typically you need the value extrapolated to 25 degrees Celcius. Temperature-EC correlation rule of thumb: about 2% more conductive per K.		* EC is temperature dependent, typically you need the value extrapolated to 25 degrees Celcius. Temperature-EC correlation rule of thumb: about 2% more conductive per K.
	* pH sensors are almost by definition fragile and last only a limited time, so probably don't bother trying to use one at all. The pH of outdoor water might not be that interesting to measure.		* pH sensors are almost by definition fragile and last only a limited time, so probably don't bother trying to use one at all. The pH of outdoor water might not be that interesting to measure.
			* I expect the non-TuYa meters to use an easier to handle bluetooth protocol, avoiding the need for complicated encryption with a key that can only be fetched for a limited time using a tuya developer account.

	== Boat control ==		== Boat control ==

2026-02-07T21:00:39Z

Water measurement probes

← Older revision		Revision as of 21:00, 7 February 2026
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	=== Water measurement probes ===		=== Water measurement probes ===
	I bought this one: Tuya compatible BT785 EC meter: https://nl.aliexpress.com/i/1005007462079781.html inexpensive, focused on EC, runs on 4x LR44		I bought this one: Tuya compatible BT785 EC meter: https://nl.aliexpress.com/i/1005007462079781.html inexpensive, focused on EC, runs on 4x LR44.

	Speaks the TuYa protocol (requires a secret key that you can fetch through the developer console).		Speaks the TuYa protocol (requires a secret key that you can fetch through the developer console).
			This is quite cumbersome: you have to register as a developer, fetch the key before time runs out and developer access is limited.

	Does NOT speak the universal serialport access protocol as described here:		Does NOT speak the universal serialport access protocol as described here:

2026-02-07T20:59:17Z

Water measurement probes

← Older revision		Revision as of 20:59, 7 February 2026
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	I bought this one: Tuya compatible BT785 EC meter: https://nl.aliexpress.com/i/1005007462079781.html inexpensive, focused on EC, runs on 4x LR44		I bought this one: Tuya compatible BT785 EC meter: https://nl.aliexpress.com/i/1005007462079781.html inexpensive, focused on EC, runs on 4x LR44

	~~Probably speaks~~ the ~~tuya serial~~ protocol:		Speaks the TuYa protocol (requires a secret key that you can fetch through the developer console).

			Does NOT speak the universal serialport access protocol as described here:
	https://developer.tuya.com/en/docs/iot/tuya-cloud-universal-serial-port-access-protocol?id=K9hhi0xxtn9cb		https://developer.tuya.com/en/docs/iot/tuya-cloud-universal-serial-port-access-protocol?id=K9hhi0xxtn9cb