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The MK484 AM radio IC is a fully functional AM radio detector on a chip. It is constructed in a TO-92 case, resembling a small transistor. It replaces the similar ZN414 AM radio IC from the 1970s. The MK484 is favored by many hobbyists. It is advantageous in that it performs well with minimal discrete components, and can run from a single 1.5-volt cell.
The MK484 has now in turn been replaced by the TA7642.
Standard operation
The simplest circuit employing the MK484 can be constructed using only a battery, an earphone (or high-impedance speaker), a coil and a variable capacitor.
Extended operation
The output of the MK484 can be fed into the base of a transistor to provide greater amplification as a class-A amplifier, however this is often an inefficient design. Conversely, the LM386 audio amplifier may be used to drive a small speaker.
Note that higher voltage is required if the LM386 is to be used. Therefore, small signal diodes (such as 1N4148) are recommended to create a voltage drop, or use a Zener DCāDC converter with a red LED (in forward, can double as a power indicator) and a resistor (several hundred ohms for 9V operation), to avoid overvolting the MK484.
Advantages
- Compact size
- Low power consumption
- Low cost: Rs 40 to 60 in Indian electronic markets
- Retails from 65 cents each on various websites
References
- "MK484 Radio IC datasheet" (PDF). Rapid Electronics Ltd.
- "Mk484 Radios".
External links
- Ferranti ZN414Z/ZN415E/ZN416E datasheet
- GEC Plessey ZN414Z/415E/416E datasheet
- Rapid MK484 datasheet
- Rapid TA7642 datasheet
- Mitsumi LMF501T datasheet
- Web site with examples of some matchbox radios based on the ZN414Z
- Another ZN414 radio
- A MK484 radio
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