Except, do not put IC1(LF351) and power output transistors Q3(2N3055) and Q4(MJ2955). The cookie is set by the GDPR Cookie Consent plugin and is used to store whether or not user has consented to the use of cookies. The cookie is used to store the user consent for the cookies in the category "Performance". This cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Other. The cookies is used to store the user consent for the cookies in the category "Necessary". The cookie is set by GDPR cookie consent to record the user consent for the cookies in the category "Functional". The cookie is used to store the user consent for the cookies in the category "Analytics". These cookies ensure basic functionalities and security features of the website, anonymously. Necessary cookies are absolutely essential for the website to function properly. And, BTW 2N3055 is an NPN transistor, not PNP as the thread’s title says… Once the flux through the feedback winding is close to zero, the voltage across the lower resistor again turns ON the transistor via the feedback coil (which at this moment presents a low impedance) – and the cycle repeats itself (i.e., the circuit oscillates) as long as the power is applied. When the transistor turns OFF, the flux through the primary starts to decay, and so does the flux through the secondary and feedback windings. The feedback winding is such that the current through it opposes the current going into the base, and therefore reduces the available base voltage – as soon as this voltage falls below 0.7 V (the transistor’s turn-on voltage), the base diode no longer conducts and the transistor turns OFF. As the transistor turns ON, flux builds up in the primary winding which is coupled inductively to both the secondary and feedback windings. When power is first applied, the transistor is OFF – the voltage across the lower base resistor turns it ON – at this instant, the feedback winding has almost zero impedance to DC. The other is via the transformer’s feedback winding’s flux once the circuit operates. One is the voltage divider which simply turns the transistor ON via the feedback winding (which basically has almost zero DC resistance). Observe the base circuit of the transistor – it has two paths.
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