Old ETI453 amp info

[yaputya]

I'm looking for the circuit and ETI article for the mini-amp ETI453 from
ETI April 1980 (also published (I think) as the HE105.)
I've got a couple of PCBs but have long ago thrown out the ETI mag.
It seems to use an op-amp, three small-signal transistors and two power
transistors, from the pcb pattern.
Any old-timers out there who can help shed any light?

 

[F Murtz]

I'm looking for the circuit and ETI article for the mini-amp ETI453 from
ETI April 1980 (also published (I think) as the HE105.)
I've got a couple of PCBs but have long ago thrown out the ETI mag.
It seems to use an op-amp, three small-signal transistors and two power
transistors, from the pcb pattern.
Any old-timers out there who can help shed any light?

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.

 

[Phil Allison]

"yaputya"

I'm looking for the circuit and ETI article for the mini-amp ETI453 from
ETI April 1980 (also published (I think) as the HE105.)
I've got a couple of PCBs but have long ago thrown out the ETI mag.
It seems to use an op-amp, three small-signal transistors and two power
transistors, from the pcb pattern.
Any old-timers out there who can help shed any light?

** Is the PCB designed to accept PSU components and two TO3 devices on
heatsinks like this:

http://media.digikey.com/photos/Aavid Thermalloy Photos/50150&501603B00000.jpg



.... Phil

 

[Tom]

I'm looking for the circuit and ETI article for the mini-amp ETI453 from
ETI April 1980 (also published (I think) as the HE105.)
I've got a couple of PCBs but have long ago thrown out the ETI mag.
It seems to use an op-amp, three small-signal transistors and two power
transistors, from the pcb pattern.
Any old-timers out there who can help shed any light?

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

 

[Phil Allison]

"Tom"

I got old "Audio Projects from ETI" mag with this amp, it uses LM301,
BC557, BC639/BC640 and TIP31/32 for output stage.

** That is the same PCB I used a few times back in the early 80s - but
modified it so TO3s (ie 2N3055 and MJ2955 ) would fit in place of the
TO220s.

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

 

[yaputya]

"yaputya"


** Is the PCB designed to accept PSU components and two TO3 devices on heatsinks like this:

http://media.digikey.com/photos/Aavid Thermalloy Photos/50150&501603B00000.jpg



... Phil

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.

 

[yaputya]

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

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

 

[yaputya]

"Tom"


** That is the same PCB I used a few times back in the early 80s - but modified it so TO3s (ie 2N3055 and MJ2955 ) would fit in
place of the TO220s.

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

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

 

[Phil Allison]

"yaputya"

"Phil Allison"

That is interesting, could you scan your circuit and post it somewhere

** After 30 years, I no longer have a copy.

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


.... Phil

 

[Yaputya]

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 [email protected] (Please put the word 'orchid' in the subject to avoid the spam filter.)

Barry

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

 

[Yaputya]

Have you built the amp yet ?

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.