Does anyone have a good sub for the LM389?

[Scott]

I decided to build a BFO before I started in on a more complex device. Downloaded the .pdf from here ( http://tthn.com/geotech/metdet/bfo/edn.html ), and hit a snag right away.


The LM389 is a discontinued semi-conductor. No sub listed in the current ECG or SK cross references. Any ideas?


TIA,


Scott

[rick]

the national data book says it is just 3 npn transistors and an audio power amp similar to lm386----get a 386 for the audio and use descrete transistors with similar specs. as those listed...


you will not have the 18 pin pcg. but should not be an overwelming obstical...if you still have troubles--repost---maybe someone has a 389--me
will look some but doubt it--


reg-rick


>I decided to build a BFO before I started in on a more complex device. Downloaded the .pdf from here ( http://tthn.com/geotech/metdet/bfo/edn.html ), and hit a snag right away.
>The LM389 is a discontinued semi-conductor. No sub listed in the current ECG or SK cross references. Any ideas?
>TIA,
>Scott

[rick]

the national data book says it is just 3 npn transistors and an audio power amp similar to lm386----get a 386 for the audio and use descrete transistors with similar specs. as those listed...


you will not have the 18 pin pcg. but should not be an overwelming obstical...if you still have troubles--repost---maybe someone has a 389--me will look some but doubt it--


reg-rick


ps:me no look at schematic but the thermal drift
of xisters ----look at lm4046 or similar as all
xisters same substrate--closer match---but still
better can be done--dual fet etc...


reg-rick


>I decided to build a BFO before I started in on a more complex device. Downloaded the .pdf from here ( http://tthn.com/geotech/metdet/bfo/edn.html ), and hit a snag right away.
>The LM389 is a discontinued semi-conductor. No sub listed in the current ECG or SK cross references. Any ideas?
>TIA,
>Scott

[rick]

ps:since a trouble on 389---a dual fet for oscillators would give better preformance because of high z-in and temp. tracking... but it seems you do not want to have maximum results---just get to work---


reg-rick


>the national data book says it is just 3 npn
>transistors and an audio power amp similar to
>lm386----get a 386 for the audio and use descrete
>transistors with similar specs. as those listed...
>you will not have the 18 pin pcg. but should not
>be an overwelming obstical...if you still have
>troubles--repost---maybe someone has a 389--me
>will look some but doubt it--


>reg-rick


>>I decided to build a BFO before I started in on a more complex device. Downloaded the .pdf from here ( http://tthn.com/geotech/metdet/bfo/edn.html ), and hit a snag right away.
>>The LM389 is a discontinued semi-conductor. No sub listed in the current ECG or SK cross references. Any ideas?
>>TIA,
>>Scott

[Carl]

Rick is correct, use an LM386 with discrete transistors. Simple 2N3904's should work fine, matching is not really critical. Thermal stability will probably suck no matter what transistors you use, but use good caps (polystyrene or polypropolene) to minimize thermal drift.


- Carl

[Scott]

I saw the reference to the lm386 my fourth time through. I will be happy to have a submersible PI unit running by May or early June.


S

[rick]

sorry scott--looked some no find though--rare one. but did a search with dogpile and go here---


http://www.dialelectronics.co.uk/l5.htm


looks like they have/had this.


reg-rick


>I decided to build a BFO before I started in on a more complex device. Downloaded the .pdf from here ( http://tthn.com/geotech/metdet/bfo/edn.html ), and hit a snag right away.
>The LM389 is a discontinued semi-conductor. No sub listed in the current ECG or SK cross references. Any ideas?
>TIA,
>Scott