I am planning use to resettable thermostat switch in my circuit. I will use it to turn off the optocoupler input. With 5 volt, current is 5-10 mA in optocoupler LED. But I'm worried that an electric arc might occur between the contacts. Electric arc can cause instability of optocoupler. Does it require debounce like in the MCU button switch event? (with capacitor)

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  • \$\begingroup\$ It won’t arc but might bounce closed (?) \$\endgroup\$ Aug 9 '21 at 11:43
  • \$\begingroup\$ I have added a scheme \$\endgroup\$
    – johny adv
    Aug 9 '21 at 12:49
  • \$\begingroup\$ The NC switch will block Triac triggering with NAND out= “1” \$\endgroup\$ Aug 9 '21 at 13:07
  • \$\begingroup\$ nc and no is not problem.Whichever is appropriate is preferred.Thermostat has two option(no and nc).The issue here is arc formation.Because of thermostat. \$\endgroup\$
    – johny adv
    Aug 9 '21 at 13:12
  • \$\begingroup\$ @johnyadv what is Vcc? \$\endgroup\$
    – Voltage Spike
    Aug 9 '21 at 17:54

Large inductance and current causes arcing. But not here with 10mA and IR LED .

These are the specs which indicates no arcing.

Features of Structure:
1.Quickly respond to the variation of temperature,
being straightforward, reliable, making no arc discharge.
2.The design is free from thermal effect of current, providing accurate temperature, long service life and low internal resistance.
Direction for Use:
1.The product is applicable to chargeable batteries, ballasts, massagers, various fractional motors, plastic package motors, transformers, apparatus, etc.
2.The product should be closely attached on the mounting surface of the controlled instrument when it is arranged in a way of contact temperature sensing.
3.Avoid the collapse or deformation of outer casings under great pressure during installment so as not to decrease the performance.
Note: Clients may choose diverse outer casings and conducting wires subject to different requirements.
Technical Parameters
Switch Type : normally closed normally opened
Operating Voltage/Current: AC250V/5A AC125/8A
Operating Temperature: 30-160C (one step for every 5C)
Standard Tolerance: ±5C
Reset Temperature: operating temperature decrease by 15-45C
Contact Closure Resistance: ≤50mΩ
Insulation Resistance: ≥100MΩ
Service Life:  10000 times


  • \$\begingroup\$ okay,I have added a scheme. \$\endgroup\$
    – johny adv
    Aug 9 '21 at 12:50
  • 2
    \$\begingroup\$ Tony - Hi, As required by this site rule, when we include something in an answer (e.g. photo, image or text) which isn't our own original work, we need to properly reference (cite) it. That text has come from somewhere else, so in order to comply with that rule, please can you edit your answer and add a link back to the original source web page? Thanks. \$\endgroup\$
    – SamGibson
    Aug 9 '21 at 14:16
  • \$\begingroup\$ Hi Tony,unfortunately I haven't remembered.I will be more careful from now on.Except this,Can I use ptc instead of thermostat? as series with the load?can ptc be selected according to switching temperature?(independent current) \$\endgroup\$
    – johny adv
    Aug 9 '21 at 14:50
  • \$\begingroup\$ TY @SamGibson I also included in question where it belongs. \$\endgroup\$ Aug 9 '21 at 15:04

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