0
\$\begingroup\$

According the the datasheet of the DFGT-03MC01, it is possible to control the flame:

"The fire will only switch on when the voltage has first been higher than 2V and then lower than 1.5V. For this, the relay is used that is also in the schematic. The voltage / flame is then adjusted between 0-1.5V and it is switched on/off with the relay. If the relay is not used, the fire must be switched off with a voltage greater than 2V and switched on with a voltage less than 1.5V."

schematic

simulate this circuit – Schematic created using CircuitLab

Question, with an ESP 32 the DAC already supplies a voltage between 0 and 3.3V. Are the resistor then still required ? I would think these are only required to step the 0-10V down ?

enter image description here

Datasheet: https://support.resideo.com/s/contentdocument/0694x00000GfrrqAAB?language=en_US

\$\endgroup\$
1

1 Answer 1

1
\$\begingroup\$

According to my understanding: yes! The purpose of the resistors are to limit the voltage to 2.2v. So whether the input voltage is 10v or 3.3v, it must be reduced to 2.2v. Nevertheless, it is said in the documentation that the device supports a maximum of 3.3v, so there is no risk of deterioration if you dont use resistors.

In concrete terms, it is necessary to

  1. measure the intensity (I) with a multimeter.
  2. Modify the formula of the voltage divider to (R1+R2) * I = 3.3v, where 3.3v is the maximum in DAC output (GPIO25 and 26) of the ESP32.

I've recently measured the intensity, it was equal to 9mA, so for me :

=> R2 = 2.2/0.009 = 244 ohms

=> (R1+R2) * 0.009 = 3.3v => R1+R2 = 3.3/0.009 => R1 = (3.3/0.009) -224 => R1 = 142.6 ohm.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.