Old ETI453 amp info

What I did after some helpful info from Phil (and some abuse) about which issue, was to join the big library in sydney (they keep copies ) and copy article.

"yaputya"

... Phil

I would still have it around here somewhere

I got old "Audio Projects from ETI" mag with this amp, it uses LM301, BC557, BC639/BC640 and TIP31/32 for output stage. If you provide working email I can scan and send you the article.

Tom

Configured it as a Wien bridge, self oscillating, sine wave power amplifier using a 6.3 volt bulb for amplitude stability. The output drove a 15 watt valve output transformer ( A&R ) in reverse to produce a 240V, 50 Hz sine wave with adjustable frequency over a narrow range.

The purpose was fine pitch tuning for a synchronous turntable.

Was published in the design ideas pages of ETI in the early 80s.

.... Phil

heatsinks like this:

No, it doesn't seem to have rectifiers etc. and has 6 pads near the edge of the pcb that would take 2 TO220 transistors, not TO3s. PCB is 83mm x 50mm, coded ETI453.

BC639/BC640 and TIP31/32 for output stage. If you

Thanks, I use a working email for ngs so just reply to sender.

BC639/BC640 and TIP31/32 for output stage.

modified it so TO3s (ie 2N3055 and MJ2955 ) would fit in

using a 6.3 volt bulb for amplitude stability. The

a 240V, 50 Hz sine wave with adjustable frequency

That is interesting, could you scan your circuit and post it somewhere (or just email it to me).

"yaputya"

Silicon Chip magazine have back issues of most EA and ETI mags and will copy articles for a small fee.

... Phil

Hi yaputya I built the ERI453 way back when and found it again half an hour ago when cleaning out my workshop. (I found your request when Googling it myself) If you're still looking for the article I'm sure I have it.

If so, email me at snipped-for-privacy@yahoo.com (Please put the word 'orchid' in the subject to avoid the spam filter.)

Barry

cleaning out my workshop. (I found your request when

the subject to avoid the spam filter.)

Thanks very much for the offer, but I've already got the ETI article from someone else on aus.electronics!

cleaning out my workshop. (I found your request when

in the subject to avoid the spam filter.)

someone else on aus.electronics!

Have you built the amp yet ?

from

cleaning out my workshop. (I found your request when

in the subject to avoid the spam filter.)

someone else on aus.electronics!

I actually built two of them about 30 years ago to replace the power amps in a stereo gramophone unit. Last year I removed them before the old unit was chucked out, they are now used to boost the speaker audio from my workshop PC. They work well enough for the job, but probably would sound even better if the op-amps were replaced with NE5534s.