The simplest radio circuit Among them, L1 and C1 form a tuning circuit, VD and C2 form a detection circuit, and L1 and L2 form a coupling circuit. The advantages and disadvantages of direct radio:
The Tact Switches, also called theTactile Push Button Switches, is used to meet the operating force to apply pressure to the switch operation direction. The switch function is closed and closed. When the pressure is released, the switch is opened, and the internal structure is realized by the force change of the metal shrapnel.
The Momentary Tact Switches has the advantages of small contact resistance, precise operating force error, and diversified specifications.We have a variety of Mini Tact Switches, including TK series, BP Series and other series. This Tactile Button offers many options on the item of circuit, comprising a single pole, single throw switch, or a single pole, double throw, double action switch.
This Push Button Switches that is PCB mounted and has a long travel. The distinctive feature is the double action of the double throw switch; It will actuates when press mid-travel and , then continue pressing for another actuation at full travel.
The applications of this Led Light Switches is including Audio and video products, digital products, remote controls, communication products, household appliances, security products, toys, computer products, fitness equipment, medical equipment, counterfeit pens, laser pointers, etc.
Tact Switches Micro Switches,Mini Switches,Micro Limit Switch,Micro Switches Types YESWITCH ELECTRONICS CO., LTD. , https://www.yeswitches.com
Signal waveform before and after detection: 
Advantages: simple circuit, small size, low cost, easy to carry and manufacture.
Disadvantages: low sensitivity and poor selectivity.
The advantages and disadvantages of heterodyne radio:
Advantages: high sensitivity and good selectivity.
Disadvantages: The circuit is complex, the cost is slightly higher, and the production is difficult.
