• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

blocking oscillator design

Not open for further replies.


New Member
Hi All,

I am trrying to design a blocking oscillator. I have a transformer that has a primary about 15 Turns and a secondary with about 500 turns. The secondary has a center tap at 10 turns that could be used for feedback.

The circuit that I tried is shown in the attachment. It work fine if I do not connect the secondary to any load, but the moment I add a bridge rectifier to the secondary, the oscillations stop and the transistor gets really hot. can someone help me with what I am doing wrong?

I guess maybe I need a transformer with an independent feedback winding? I was hoping I could use the transformer I have with a tapped secondary.
In the schematic P$4 & P$2 were the places where I was attaching the bridge rectifier (1n4004 diodes in a full wave bridge)




New Member
Hi, I had a quick look at your schematic, and at first glance, nothing appears wrong with the design. However, I would recommend that you check out other circuit designs, such as this one @ instructables
. It worked reasonably well when I tried it.
Hope this helps!


New Member
It may help someone in the future, but the original poster has been gone for over six years.


Be careful with anything you read on destructables er I mean instructables - they're often written by people who know nothing or worse, they think they know more than they do.

That circuit looks fine though.
Not open for further replies.

Latest threads

EE World Online Articles