IY CF210SP AM FM Radio Kit Electronic Assemble Kit For Electronic Learner Here is the connection diagram ... CF210SP is a new type of radio FM, AM two band radio, the FM band using the CD9088 chip, which uses patch element SMT package, the receive frequency range of 76-108HMZ. Not only to accept the FM radio, can also receive campus radio & part of the audio signal of the television stations. AM band using direct IC the TA7642, receive frequency range is 525-1605KHZ circuit is simple, assembly success rate, a better selectivity having a little;. amplifier circuit using TD2822 special function ICs having loud. Sound quality is good. Circuit works: 1. Frequency Modulation (FM) section CD9088 is a dedicated single-chip FM radio chip, Its simple external circuit, the circuit was built frequently 70KHZ phase locked loop system, selectively implemented by active RC filter, mute circuit can be suppressed non-IF signal & the IF signal is too weak. FM signal input circuit rod antenna C8 / C10 & L1 IC1 11, 12 feet into the mixer circuit, local oscillation circuit uses a variable capacitor CA / L2, etc. vitality can be achieved manually tune. Circuit R2 / C2 to squelch circuit, 3 feet to the audio loop filter capacitor C4. Indirect C13 6, 8 feet of the intermediate frequency feedback capacitor, 7 feet is connected to C14 was the low-pass capacitors, between C17 of 8/9 feet is IF coupling capacitor 10 feet connected to the C12 is a limiting amplifier low-pass capaci