View Single Post
Old 6th Sep 2010, 10:10 am   #7
Neil Purling
Join Date: Jul 2005
Location: Hull, East Yorkshire, UK.
Posts: 2,002
Default Re: Transistor Choice in radio project

How do your Mullard reference books rate the hfe of the OC71 & OC75?

I bought a kit of bits. The kit is to build a radio from a circuit in a book.
The audio stage has the emitter of the first OC71 wired to the +ve rail, no emitter resistor.
I wondered why there wasn't something with its associated bypass capacitor.
The supplier of the kit has tweaked the circuit to add a 1K emitter resistor & 22uf bypass and employ OC81's in place of the two OC71 transistors.
I am trying a emitter resistor & bypass with the OC71's in case this makes an improvement without fitting OC81s.
If the audio stage is weak as originally planned with OC71's I will make note and move on based on what help I get here.
Neil Purling is offline