# I have question marks about my power supply circuit anyone can help?

#### turgut

Nov 8, 2022
24
Im designing a power supply but its my first design as high power. I have a device and its frequency is 22-25kHz. Im designing a filter and power supply for it. So device need 600mA 12V nearly.
Question-1: Is my filter okey for that?
Question-2: This circuit could get 600mA? (output regulator will LM317 or 7812)
Question-3: What kind resistor should i use for 50ohms. Im open for suggestions.

LTSpice results below the text.

Thank you all..

#### crutschow

May 7, 2021
661
What signal/noise are you trying to filter?
Can't know if the filter works without that info.

Typically for AC analysis you use an AC voltage of 1V not 220V.
That way the output is given in dB relative to 1V.

Where is there 50 ohms?

#### turgut

Nov 8, 2022
24
What signal/noise are you trying to filter?
Can't know if the filter works without that info.

Typically for AC analysis you use an AC voltage of 1V not 220V.
That way the output is given in dB relative to 1V.

Where is there 50 ohms?
Im try to converting 220vac to 12vdc. The device's values are 12vdc input and 600ma and works near 22-25kHz. Filter for it
50ohms as snubber with cap.
So how can i get 12vdc 600ma as output.
I changed a bit new circuit like that..

my ripple voltage:

and my frequency measuring (im measuring from red arrow. i hope im doing it right.):

Last edited:

#### Ylli

Jun 19, 2018
386
V1 is the 220 VAC 50 Hz source? The voltages in LTSpice are Peak voltages, if you are connected to the 220 VAC line, the peak voltage will be 311 Vac. Why are you concerned about the frequency response between V1 and the primary of the transformer? The only thing going through that path is 50 Hz.

If the device you are powering draws a pulsing load at 22-25 KHz, you might want to add a bit more bulk capacitance on the outout of the LM317. Parallel a 1 uF and a 10 uF across that 100 nF.

Post the .asc file.

#### turgut

Nov 8, 2022
24
V1 is the 220 VAC 50 Hz source? The voltages in LTSpice are Peak voltages, if you are connected to the 220 VAC line, the peak voltage will be 311 Vac. Why are you concerned about the frequency response between V1 and the primary of the transformer? The only thing going through that path is 50 Hz.

If the device you are powering draws a pulsing load at 22-25 KHz, you might want to add a bit more bulk capacitance on the outout of the LM317. Parallel a 1 uF and a 10 uF across that 100 nF.

Post the .asc file.
Yes V1 is 220Vac 50Hz source, when im measuring ripple voltage im writing Amplitude 220V-50Hz and when im measuring frequency im doing AC Amplitude 311V-50Hz and deleting amplitude 220v.

Im not concerned but there is a filter inside the device. this is filter's image. so instead of this kind on tap filter. im trying to join my own filter inside the device's pcb.

#### WHONOES

May 20, 2017
1,216
Why do you think you need an extra filter?

#### turgut

Nov 8, 2022
24
Why do you think you need an extra filter?
device will work inside a couple of devices like pumps, monitors, converters etc. so im thinking if they can interfere with each other. im making sure to protect pcb.

#### Jodie25

May 31, 2023
2
Regarding your first question for a power supply filter, a typical approach is to use a combination of capacitors and inductors. You can also consider incorporating a low-pass filter to attenuate the high-frequency components.
For Question 2, circuit delivery levels depends on the specific components you use. Ensure the power dissipation abilities of the regulator LM317 or 7812 you plan to use and esure the regulator can handle the load safely.
For Question 3, with a 50-ohm resistor, you have options to use a standard through-hole resistor or surface mount resistor. Select a resistor with the maximum power dissipation with suitable tolerance features. Common resistors are 1/4-watt, 1/2-watt, and 1-watt ratings.

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