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Small power supply with B+ delay using the Tentlabs MEC (Mini Electronic Choke)

Tentlabs (Guido Tent with the help of Menno Vanderveen) created a series of electronic choke emulators, intended to replace big heavy filter chokes in power supplies for tube amplifiers.

A while back I designed a small power supply PCB that uses the MEC-series chokes.  More recently, I designed a version with a delay circuit to delay the B+ for some time after heater power is supplied. I used this in a 307A DHP (triode-connected) stereo desktop amp.

It's intended to support a small stereo amp or preamp.  It has a single rectifier circuit and two filter sections, so it provides two B+ outputs.  I designed it using the MEC-100 e-choke, which supports 100mA.  This seems to have been replaced by the MEC-200, supporting 200mA. So you can probably use this for up to 200mA per channel - but you probably want to increase the capacitors, probably 220uF.  Note that you need to use caps rated for the B+ voltage you plan to use.

The B+ delay is switched by a DC solid state relay, CPC1779 from Ixys. It is a bit expensive - around $11 - and can be a little hard to source.  At the time I write this Mouser and DigiKey are out of stock. I like to use a service called to locate parts - you can find the CPC1779 here:

  Here is the circuit:

You can also download a PDF file of the schematic here.  And a simple parts list (BOM).

Here are the dimensions of the bare PCB:


You can buy the PCB in my eBay store. The MEC-100 seems to have been replaced by the MEC-200.  It can be purchased directly from Tentlabs: