Substitude an Potentiometer - Automation

[alec_t]

My gut feeling is that 1/8 W smd might be a problem because of (a) resistor heating and/or (b) breakdown voltage. Any experts out there?
Certainly 330 would give lower instantaneous power loss than 220, but could result in slower switching of the triac and accordingly greater rms power loss. Might be worth doing a simulation to decide the effect of resistor change.

 

[Freiheitpt]

hmmm. If I'm not mistaken, i think these are sensitive gates. It would need only a little bit of current to switch them on. Let me take a quick look at the little PCB I have here. Forgot to look there.


EDIT:

on the PCB: (Dont mind the Diode i have there, in the wrong direction. it is a diac)

**broken link removed**

all resistors are over 1K.

 

[panic mode]

hmmm, you can do that...
with price of resistors in pennies, can't blame anyone for not bothering with this. see this:

https://canada.newark.com/bourns/cr1206fx2200elf/resistor-thick-film-220ohm-250mw/dp/01J3162
https://canada.newark.com/panasonic/erj8enf2200v/resistor-thick-film-220ohm-250mw/dp/64R5450

if you are concerned about power dissipation (which is valid reason), why not build prototype and be SURE what to expect?
also if you insist on 1/8W resistors, you can combine two to replace one 1/4W...

 

[Freiheitpt]

sorry, but maybe u didnt fully understand my bad english
The design above is from a controler from a air pump i already got here. But I want to control the air pump with an microcontroller.

I was also thinking to use 1/4 watt, or 1/3 watt resistor I found as SMD.
The only thing is about the value. Maybe I will do what you said: Try both resistors, 220Ohms and 330Ohms. =)

Thanks

 

[Freiheitpt]

deleted: double post

 

[alec_t]

Post deleted.