Doram Distortion Meter

Hi everybody a fellow of mine has found this instrument . Used to work , it was used to test distortion while designing audio power amp, mfctd circa 1975.
No other infos.
Looking for information about it , how to use it, possibly a manual.
thank a lot.

Articolo Soft start per lampade alogene

Su infoportal ho pubblicato un breve articolo sulla costruzione di un semplice Soft start per Lampade alogene a bassa tensione.
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