Thanks for that, you've just saved me some work. I'm playing with a
TDA2005 bridge audio amplifier for 10 watts off a 12v rail (since I had
one spare), but that older device is a bit prone to instability into
anything other than a perfect resistive load.
The simplicity of the LM1875 circuitry makes the effort of using a 30V
rail (via a switch mode PSU from 12V) worthwhile.
Farnell do this device too, and also I see in their catalogue the LM1876
which appears to be a pair of '1875 types in one package. 50 watts
from a bridge perhaps ?
On the subject of linear amps. I'm also investigating the idea of a
pulse width mod. voltage controller for class D PAs. Then by separating
out envelope and phase information from complex modulation waveforms, an
efficient PA could be used without the trouble of going through SSB
driver stages and probably a transverter. The authors of a lot of the
modem software could hopefully be persuaded to make amplitude and phase
info available separately.
Watch this space.
From: Andre' Kesteloot[SMTP:[email protected]]
Reply To: [email protected]
Sent: 2000-05-03 13:17
To: [email protected]
Subject: Re: LF: beacon power control
Rik Strobbe wrote:
> As the beacon is meant to be low-power (10mW and less) a relative
> power can be used (50 Watts and less), so it can easily be
> to provide extra safety.
Maplin has a small class A amplifier using a LM 1875 that easily puts
watts at 136 Khz. It is stable, has automatic current limiting and
protection. Because it operates in class A, the output can be
controlled simply by a step attenuator at the _input_ of the
The Information contained in this E-Mail and any subsequent correspondence
is private and is intended solely for the intended recipient(s).
For those other than the recipient any disclosure, copying, distribution,
or any action taken or omitted to be taken in reliance on such information is
prohibited and may be unlawful.