MOOG Etherwave Plus LED redirect?

Personally, I prefer replacing the power switch with one which has an integrated LED. They are available for around 4€ and you can choose between a red or a green LED. This is easier to install and does not require drilling an additional hole in the front panel. - Thierry

Thanks Thierry, what a fine idea!

"Oh lord, this is making me seriously rethink using Bourns 6300 parts in my stuff.  I suppose it's time to somehow characterize them in terms of temperature with the stone age equipment I've got laying about.  *Sigh* " - Dewster

Am I missing something here ? - I dont see the connection between power drawn post-regulator and the 6300 inductors!

As I understand it, Thierry is saying that the extra circuitry on the EW+ down-stream from the regulators makes this instrument more "sensitive" - the LED being the final straw pushing the regulation close to its limits..

I find this shocking to be honest - but am not surprised.. Power supplies are often the weak link in many designs... IMO, one should have at least an additional 50% capacity from the PSU, so there is no possibility of stupid problems like this... Its crazy! Something like a theremin where operating conditions are so critical, and adding / removing a LED changes performance !?  10mA to screw things up ?!?! -

The EW uses piddly little 100mA regulators doesnt it? - These are, IMO, nasty little parts if one is looking for stability, particularly if running close to their limits - they simply dont have the ability to dissipate adequately from their to92 package..so temperature fluctuates as a function of power drawn. I dont like simple 3 terminal regulators like the 7812 for anything critical (much prefer the LM317 adjustable type regulators with some additional circuitry to improve regulation) but would perhaps changing the 78L12 / 79L12 to bigger 7812 / 7912 perhaps improve performance ?

Fred.

Thierry, my Etherwave has a power supply with the grounded DIN plug/socket.
Now I've been looking at the circuit diagram of the BigBriar Etherwave Service Manual and it seems to indicate that the voltage in is 14VAC (@200mA) before the voltage regulator circuitry and the main on/off switch is in line with this input.
Does that mean I should be looking for a mains switch with a normal 'lamp' to illuminate it rather than a LED low voltage switch or should I just go back to fitting a LED to the front panel (which I would prefer not to do)?

Roy, these 14 VAC give +/- 19V peak voltage when rectified by the two diodes. Thus you'll find +19V DC at one of the two big electrolytic capacitors and -19V at the other. Taking the +19V, an 1.8k resistor, a normal LED and ground will do it since the rectifier diodes and the capacitors are behind the power switch. Don't make things more complicated as they are! ;-)

Or, as my Dad often said to me: "Don't try to discuss, you know that I'll always be right at the end."

"Am I missing something here ? - I dont see the connection between power drawn post-regulator and the 6300 inductors!"  - FredM

I guess I'm worrying out loud and in general re. temperatures & coils.  Need to stick my tankless oscillator in the freezer, fridge, and in a box with a light in it to see what kind of behavior shakes out.  Do you have any temperature data on the 6300 Fred?

Ahhh...Thierry!
My mistake!
I misunderstood the nature of the LED switch-I had assumed that the switch itself had a polarity.

Always learning! :-)

Roy, these switches have two independent extra pins for the LED... ;-)

"Do you have any temperature data on the 6300 Fred?" - Dewster

No - Like most inductors, data from the manufacturer is almost nill.. I thought I had roughly determined its charactaristics from evaluating it using my ATE while I cycled its temperature, but since then have concluded that my test set-up was not reliable.

So all I have is the certainty that they behaved better than any other inductors I tested - but I never tested Miller parts.

At the time I was deeply into magnetic components, working on saturable reactors - this included putting an extra winding on the 6300 through which I passed a DC control current.. I have now given up on all that - There are so many possible thermal drift sources at the theremin front-end that I decided to simply have a thermal sensor covering the lot, and derive a correction voltage from this which could be mixed in to compensate whatever the sum of errors turned out to be.

Having real data would be great - I hope to be in a position to do these tests in future - but for now I cannot give any numbers because I dont trust any of them .. At one time I was getting excellent results from common-mode power chokes, which later proved to be absolutely abysmal!

Fred.

Hello friend ! This is Henry ! The PCB manufacturer from China .

Our site : www.szte-pcb.com , my email : henry@szte-pcb.com , my skype : henrypi2012

Thierry wrote: Personally, I prefer replacing the power switch with one which has an integrated LED. They are available for around 4€ and you can choose between a red or a green LED. This is easier to install and does not require drilling an additional hole in the front panel. - Thierry
Digikey has a direct replacement switch with a red LED; part number CKC2017-ND.  This snaps in the switch cutout and looks just like the old switch.  Run the power wire that always has voltage to the lowest contact and the switched wire to the contact in the middle. Connect the middle contact to the one directly above it which is one leg of the LED. Solder a 1K resistor on the final  contact on the right to ground on the output jack.  Fiat lux!

Choose USPS shipping from digikey which came to $2.68 for my order.