[SOLVED] DC supply becomes sawtooth when LOAD is applied

[jishnuprakash]

hi,
I observed this problem in one of my devices which basically sense water and turns on a valve
problem is when the valve turns on supply to the coil becomes saw tooth
before

After

what could be the problem , we are using a SMPS 230VAC to 24VDC and Flyback transformer
has 2 output one 24V and other 15V , 24V is driving only this coil and an LED
15V is used to power microcontroller parts,

 

[Easy peasy]

looks like your 24V supply is a bit flakey ....

 

[jishnuprakash]

looks like your 24V supply is a bit flakey ....

is it due to current capability of SMPS being low or any other issue please elaborate

 

[FvM]

You didn't show power supply primary side, so we can only guess. Are you sure that the solenoid is permanently enabled during the test, not switching with about 160 Hz?

 

[jishnuprakash]

You didn't show power supply primary side, so we can only guess. Are you sure that the solenoid is permanently enabled during the test, not switching with about 160 Hz?

the image you are seeing is when solenoid is enabled video below shows how signal changes

the video below shows

 

[dick_freebird]

Lousy output filter and a cross-regulating control loop?

 

[Easy peasy]

given the time base in the mS region - there is not enough bulk storage on the mains side of the switcher - of the solenoid is overloading the output you are using ... (?)

 

[jishnuprakash]

hi,
I increased the output filter capacitor value and able to solve the issue