The MK484 AM radio IC is a fully functional AM radio detector on a chip. It is constructed in a

TO-92 The TO-92 is a widely used style of semiconductor package mainly used for transistors. The case is often made of epoxy or plastic, and offers compact size at a very low cost. History and origin The JEDEC TO-92 descriptor is derived from the or ...

case, resembling a small

transistor upright=1.4, gate (G), body (B), source (S) and drain (D) terminals. The gate is separated from the body by an insulating layer (pink). A transistor is a semiconductor device used to Electronic amplifier, amplify or electronic switch, switch ...

. It replaces the similar

ZN414 The ZN414 is a low cost, single-chip AM radio integrated circuit. Launched in 1972, the part was designed and supplied by Ferranti, but was second sourced from GEC-Plessey. The ZN414 was popular amongst hobbyists, as a fully working AM radio co ...

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 Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery ...

. The MK484 has now in turn been replaced by the TA7642.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 A variable capacitor is a capacitor whose capacitance may be intentionally and repeatedly changed mechanically or electronically. Variable capacitors are often used in L/C circuits to set the resonance frequency, e.g. to tune a radio (therefo ...

Extended operation

The output of the MK484 can be fed into the base of a

to provide greater amplification as a

class-A amplifier In electronics, power amplifier classes are letter symbols applied to different power amplifier types. The class gives a broad indication of an amplifier's characteristics and performance. The classes are related to the time period that the active ...

, 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 Voltage drop is the decrease of electrical potential along the path of a current flowing in an electrical circuit. Voltage drops in the internal resistance of the source, across conductors, across contacts, and across connectors are undesirab ...

, or use a Zener DC–DC 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

External links

Ferranti ZN414Z/ZN415E/ZN416E datasheet

GEC Plessey ZN414Z/415E/416E datasheet

Rapid MK484 datasheet

Rapid TA7642 datasheet

* ttp://www.zen22142.zen.co.uk/Circuits/rf/ZN414.htm Another ZN414 radiobr>A MK484 radio
Linear integrated circuits {{electronics-stub