power supply 684j/400v

[kik]

hello everybody
please somebody help me to make 5v power supply without usung transformer because i saw a circuit that using just this compenent(684j/400) and only a bridge diode and i don't know nothing about this component
and this is the image

 

[Genovator]

This is a polypropylene capacitor with rating of I guess 680nF 400v.... This capacitor is used for current supply. You should definitely see a high value resistor, say around 1Meg ohm in parallel with this. This circuit is nothing but just reducing the voltage by limiting current with the resistor, then adding this capacitor to get appropriate current. It is a sensitive balance between voltage & current. This setup cannot be considered as a pure 5v source. This device is designed as per the current requirement. Its is meant for low current supply...
Here is a note I once made...

 

[jpsganesh]

In this method electrical isolation won't be tre. so when we work with this power supply we should be very careful.

Ref:

**broken link removed**

https://ww1.microchip.com/downloads/en/appnotes/00954a.pdf - very good link. It has complete detail with calculation

https://en.wikipedia.org/wiki/Capacitive_power_supply

**broken link removed**


Google it with this key word "power supply without transformer" you will get more details and calculation.

 

[schmitt trigger]

This power supply is based on a capacitor's reactive impedance.

Since it is a Voltage divider, the load current is of utmost importance when choosing the capacitor value. For a varying load, the output voltage will vary wildly. This is the reason that these types of supplies are mostly used on constant loads (i.e. leds).

Also, as JPSGANESH mentions, there is no electrical isolation from the mains and the output will be live.

- - - Updated - - -

This power supply is based on a capacitor's reactive impedance.

Since it is a Voltage divider, the load current is of utmost importance when choosing the capacitor value. For a varying load, the output voltage will vary wildly. This is the reason that these types of supplies are mostly used on constant loads (i.e. leds).

Also, as JPSGANESH mentions, there is no electrical isolation from the mains and the output will be live.

 

[kik]

thank you all for helping me
i will try to realize it and i hope that it work with me but if doesn't work i will be very angry hh
all my best regard and thank you all

 

[kik]

can this circuit drive a microcontroller??
because i tried that but it doesn't work
can anyone help me to make 120v power supply and drive a microcontrooler with 5V power supply??

 

[blueroomelectronics]

Just buy a cell phone adapter. They're usually 5V and fairly cheap.

 

[kik]

and what about 120v??

 

[jpsganesh]

Microcontroller will work with this power supply. But it is too risk operating a Micro Controller with these type of power supply.
* No Electrical Isolation
* More noise in the supply
* Supply voltage may vary (not a fixed volt). u can use LDO eventhough the supply voltage go lessthan desired volt or min req volt for the LDOs
* Controller may get reset frequently due to electrical disturbance