This circuit is from a 1947 Radio Electronics. The 4-tube circuit is battery powered and uses a crystal phone.
This circuit indicates when a rain is acidic by monitoring its pH. The circuit is from a 90s RE...
Chinese 基本信息 > 出版社: 科学 (2007年4月1日) 平装 语种: 简体中文 ISBN: 7030186605 条形码: 9787030186607 品牌: 博库 ASIN:...
This transmitter uses a small loudespeaker (FTE) as microphone and can send the signals to...