Virtual battery operation ?

Just as a guess, flash memory?

David.

An

C2000

metal

From the C1000 repair and user manual you press a button to opt for battery operation for no mains hum/ fridge spikes etc presumably (if/after the battery is charged off the mains) or opt for mains power to the preamp. So I assumed the same with the C2000 but no battery or battery switch or anywhere obvious a missing battery could be/have been connected/located. If it was not for Technics make and going by the heavy lump of metal, for no functional purpose, I would have said it was a con.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

Shades of the 1920s and 30s, when battery operation was preferred by some "audiophiles" of the day (because "mains sets hum"). But I thought that attitude had died out decades ago, apparently not.

(if/after the

I had assumed before that the battery was to back-up settings, hence my comment about flash memory. If the VBO is intended to run the pre-amp, but there is no battery, and no mains supply, I can only guess that in VBO mode the pre-amp is entirely passive.

I'm not sure that just because it has a well-known name on the front you can necessarily assume that it's not.

David.

It's a very clean power supply, virtually as good as a battery as regards supply noise.

Technics have this used all over the place, from pre-amplifiers to CD, DVD and Blueray players.

More info here

Ah!... we're back in bullshit territory again :-(

David.

:-)

The next topic is "VC-4 Amplifier System" - found plastered on the front of my Technics tuner.

for no

Looks like a regular linear ps to me except for the transformer being about

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

I was wrong in calling it a "very clean power supply". I should have said "it has the effect of a very clean power supply"....

Have a look around the preamp section. As from the link I gave (from google), it's not a regulator but an "active filter".

Quote "tracks input voltage as changed by variations in line voltage and load, and takes out some AC. That may be useful under some special circumstances. In the tube days, this was done using a large choke, that's in a way what this circuit simulates."

FWIW I tried a patent search. Got nothing.

about

There are 2SD2037 and 2SB1357 ,probably as pass transistors downstream of the 18V regulators, using some of the headroom to drop to +/- slightly lower rails and a load of little electros, which doesn't strike me as particularly groundbreaking, let alone simulating a battery.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

Doesn't sound anything special. 78M18 and 79M18 are bog-standard regulator chips.

Active filters in power supplies are common when low ripple is required but voltage stabilisation is not required. At it's simplest it's just an emitter follower with the base fed from the input via a resistor and decoupled to ground by a large capacitor. If the current loading is high a compound transistor (darlington pair) might be used. Again nothing special there, they've been used for years (thermionic version were in use before the invention of the transistor).

Not original enough to be patentable.

David.