Build a One-Transistor MC Step-up

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With modern low-noise transistors, you can build an MC step-up with only one transistor.

The MC step-up is powered by a 12V lead-acid battery. The value of R4 depends on the hfe of the transistor used.

Transistor--R4 -- hfe -- Relative Noise for transistor

The brand of the transistor is very important. I found that Philips MPSA 42 and Philips BC 639 are 5-10dB more noisy than Motorola. Distortion of the amplifier is low due to local feedback. The gain of the amplifier is 19-20dB. If you have a problem with radio frequency interference, place a 22nH inductance in series with C1 and a 22pF capacitor in parallel with R4.


  1. C1 2.2uF polypropylene
  2. C2, C3 1uF polypropylene
  3. R1. R2 120-ohm wirewound
  4. R3 1200-ohm

Above: Fig. 1: Step-up circuit.

Above: Fig. 2: Pinouts for different transistors, bottom view.

Next: Two-Transistor MC Phono Step-up


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Updated: Sunday, 2016-02-07 22:19 PST