Q&A

摘要

Q Can you please help with a simple diagram for the FM radio shown in Figure 1 ? I would like to add an LM386 amplifier - less than or equal to one watt - with minimal parts and an eight ohm speaker to it. I'd like to eliminate the need for a 'crystal earphone,' using just one power supply - that of the FM radio or from a wall wart (9 VDC @ 100 mA). Since I couldn't locate an original 365 pF variable capacitor at an affordable price, I substituted one rated 0-532 pF. Consequently, do I need to change the value of C4? Also, I couldn't find the two metal PNP transistors (25A220). Can you please recommend other substitutes, without modifying the entire diagram?