СГ2С Russian voltage regulator test

Here is a quick test of a russian СГ2С (SG2S) 75V voltage valve regulator:

The CCS is a classic cascoded DN2540 MOSFET. A russian PIO capacitor is bypassing the regulator and the input impedance is the Pete Millet’s interface impedance. HT is a well regulated variable power supply.

When near maximum bias current is achieved (circa 30mA), the noise floor is surprisingly low: -85.5dB / 53uV.

Need to capture input of power supply at the CCS input 🙂

Edit: after measuring the power supply noise level and finding that is near -90dB, came up to the conclusion that the above noise level is the VR noise. Quite good for a simple (but effective) voltage regulator. Gary Pimms used this configuration many times on his designs…


Upon request from Vyacheslav, here is the noise analysis for different current points:

As you can see it’s very linear. There is a 4dB difference between 5mA and 40mA.

Also tested ripple attenuation using a poor-regulated HT power supply. Here are the interesting results:

  • 62dB @50Hz
  • 80dB @100Hz



6 Replies to “СГ2С Russian voltage regulator test”

  1. Hi Alejandro,
    very interesting analysis СГ2С!
    ripple -85.5dB / 53uV – if the current is 30 mA,
    but what level ripple – if 5mA, 10mA, 20mA, and 40mA (when the maximum current)? you have the measurements?
    I want to know when (level current) minimum ripple noise?

    P.S. they also have nice illuminated 🙂

    Ukraine, Dnepropetrovsk

    1. Hi Vyacheslav,
      No, I don’t have. Did a quick test, so will try to measure noise level at different currents.

  2. Ooo, the linear response!
    Alejandro. Many thanks!
    Photo – looks very good 🙂 balloons glow (neon-argon mixture) 🙂
    Yes, a good stabilitron (VR) – and the price is low … for example, in Ukraine (in Dnepropetrovsk, the radio market), only 0.5$ 🙂

    Vyacheslav, Ukraine, Dnepropetrovsk

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