Abstract: This invention pertains generally to the field of chemical synthesis and purification, and more specifically to methods of synthesizing and purifying certain 3,7-diaminophenothiazin-5-ium compounds (referred to herein as “diaminophenothiazinium compounds”) including Methythioninium Chloride (MTC) (also known as Methylene Blue). In one embodiment, the method comprises the steps of, in order: nitrosylation (NOS); nitrosyl reduction (NR); thiosulfonic acid formation (TSAF); oxidative coupling (OC); Cr(VI) reduction (CR); isolation and purification of zwitterionic intermediate (IAPOZI); ring closure (RC); chloride salt formation (CSF); one of: sulphide treatment (ST); dimethyldithiocarbamate treatment (DT); carbonate treatment (CT); ethylenediaminetetraacetic acid treatment (EDTAT); organic extraction (OE); and recrystallisation (RX). The present invention also pertains to the resulting (high purity) compounds, compositions comprising them (e.g.

Abstract: In a method of auto-tuning a radio FM-receiver the receiver frequency band is scanned until a FM signal is received meeting criteria for identifying the signal as being of a predetermined quality, particularly coming from a valid FM station. At least during tuning it is permanently established whether or nor the FM signal meets the criteria, whereafter the results thereof are read a predetermined number of times, and the FM signal is only stored if at least most of these times the criteria are met. Particularly, the results are read 10 times and the FM signal is only stored if at least 8 times thereof the criteria are met.