Is that circuit is a joule thief ?

Thread Starter

Medhat Hmada

Joined Jul 28, 2019
13
Hi
The circuit with attach i thank joule thief , but it use two PNP transistor medium power TIP140 with coil center tapped 8-0-8 turns with the input and 30-0-30 turns with output
I do not understand the connection between each base with 30 wire?
Thankssimple dc-dc boost converter.jpg
 

bertus

Joined Apr 5, 2008
20,739
Hello,

Where did you get the drawing?
Write out a schematic and you will see that the base and collector are swapped.
The ouput can not be on the base.

Bertus
 

Thread Starter

Medhat Hmada

Joined Jul 28, 2019
13
Hello,

Where did you get the drawing?
Write out a schematic and you will see that the base and collector are swapped.
The ouput can not be on the base.

Bertus
Thank you Bertus for your reply
That drawing i get it from an Indian site.
i made it practically and i get 9V
I try hardly to understand your PDF file with unregulated push-pull converter
But that drawing is different , the input is not isolated from the output!!!! because the base of each transistor connected to the output.
another hint: the output here is regulated!!!!!
 

Thread Starter

Medhat Hmada

Joined Jul 28, 2019
13
Long time ago i made the unregulated push-pull converter with in the attach file
 

Attachments

ci139

Joined Jul 11, 2016
1,696
BD140 has Abs. Max. for I.B -500mA . . . Li-Ion can give out over 5A when fully charged . . . your 8:30 transformer gets it in the "worst case scenario" down to about 2.5A ??? unless the thing switches fast enough ??? for the collector windings to never reach the excessive currents . . . i suggested the pg.45 coz the design is more safe for the circuit components
 
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