Comments on: 5V Transformerless DC Power Supply from 220V with LM2575 https://powersupply33.com/transformerless-power-supply-from-220v-with-lm2575.html PSU, Battery Charger, Inverter Fri, 22 Jul 2016 09:27:12 +0000 hourly 1 By: sma https://powersupply33.com/transformerless-power-supply-from-220v-with-lm2575.html#comment-38788 Fri, 22 Jul 2016 09:27:12 +0000 http://powersupply33.com/?p=539#comment-38788 hi
can i use irf740 or irf740b?

]]> By: eli98pe https://powersupply33.com/transformerless-power-supply-from-220v-with-lm2575.html#comment-37853 Sat, 05 Dec 2015 13:24:15 +0000 http://powersupply33.com/?p=539#comment-37853 Very interesting circuit, however, a think it is not going to work very well, look at T2 ( BUZ41A or IRF730) , both have a maximum 20V VGS, so when voltage get bigger than 20 , T2 gate get damage .

]]> By: Mile NS https://powersupply33.com/transformerless-power-supply-from-220v-with-lm2575.html#comment-4223 Sun, 06 Jan 2013 18:51:03 +0000 http://powersupply33.com/?p=539#comment-4223 In reply to stsn.

As I know this power supply is “Elektor” design, and they said it’s capable for 1A!
I have build it 3pcs, few months ago, and they are working excellent, but connected loads draw “only” 400mA , everything is cool. I have added small heatsink to T2, but don’t know is it even necessary?

Be careful, connected to main’s voltage and don’t touch any parts during work !!!

]]> By: Mile NS https://powersupply33.com/transformerless-power-supply-from-220v-with-lm2575.html#comment-4222 Sun, 06 Jan 2013 18:43:35 +0000 http://powersupply33.com/?p=539#comment-4222 In reply to liam.

Hi Liam.

T1 should be standard NPN transistor – BC547 (TO-92) and T2 is BUZ41a (TO-220) or You can use IRF730.
Also, my recommendation for R3 is to use higher power one, 2W would be fine.

Circuit is connected directly to the MAINS voltage and it’s all over components, so it is very dangerous to use!
All parts are LIVE and should never be touched, neither wires while you connecting load to this power supply!

Greetings from Serbia.

]]> By: stsn https://powersupply33.com/transformerless-power-supply-from-220v-with-lm2575.html#comment-3089 Thu, 18 Oct 2012 11:32:56 +0000 http://powersupply33.com/?p=539#comment-3089 please what is the power(current) capability of this circuit.?

]]> By: Chinna Durai A https://powersupply33.com/transformerless-power-supply-from-220v-with-lm2575.html#comment-2853 Wed, 12 Sep 2012 11:45:19 +0000 http://powersupply33.com/?p=539#comment-2853 Hi
Could any body suggest me the resistor R1,R2,R3,R4 & R5 , D1 , T1 & T2 values for an output voltage of 25V which is given as input to the LM2575. And also pls suggest me the VD1 rectifier component name and its specifications for current rate of 2A.

]]> By: liam https://powersupply33.com/transformerless-power-supply-from-220v-with-lm2575.html#comment-677 Fri, 28 Oct 2011 17:22:05 +0000 http://powersupply33.com/?p=539#comment-677 Hi, can you specify T1 and T2?
Thanks.

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