The ZN414 is a low cost, single-chip AM radio integrated circuit. Launched in 1972, the part was designed and supplied by

Ferranti Ferranti or Ferranti International plc was a UK electrical engineering and equipment firm that operated for over a century from 1885 until it went bankrupt in 1993. The company was once a constituent of the FTSE 100 Index. The firm was known ...

, but was second sourced from GEC-Plessey. The ZN414 was popular amongst hobbyists, as a fully working AM radio could be made with just a few external components, a crystal earpiece and a 1.5 V cell. The original ZN414 chip from Ferranti was supplied in a 3-pin, metal

TO-18 In electronics, TO-18 is a designation for a style of transistor metal case. The case is more expensive than the similarly sized plastic TO-92 package. The name is from JEDEC, signifying ''Transistor Outline Package, Case Style 18''. Constructi ...

'transistor' package, whereas the GEC part and later Ferranti ones (ZN414Z) used the plastic

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 ...

encapsulation. Later variants, the ZN415 and ZN416, came in 8-pin DIL packages and included a built-in amplifier that could drive headphones and small speakers directly. The radio circuit inside the ZN414 is based on a design known as

Tuned Radio Frequency A tuned radio frequency receiver (or TRF receiver) is a type of radio receiver that is composed of one or more tuned radio frequency (RF) amplifier stages followed by a detector ( demodulator) circuit to extract the audio signal and usually ...

(TRF). The TRF design is much simpler than the popular, but more complex,

superheterodyne A superheterodyne receiver, often shortened to superhet, is a type of radio receiver that uses frequency mixing to convert a received signal to a fixed intermediate frequency (IF) which can be more conveniently processed than the original carri ...

radio circuit often used in modern AM receivers. It is principally the use of the TRF circuit that allows almost a whole radio to be fitted into one small, three pin package. The manufacturing process for the ZN414 chip used a relatively new (for the time) technique known as

Collector Diffusion Isolation Collector(s) may refer to: Arts and entertainment * Collector (character), a fictional character in the Marvel Comics universe * ''Collector'' (2011 film), a 2011 Indian Malayalam film * ''Collector'' (2016 film), a 2016 Russian film * ''Collec ...

(CDI). CDI was invented by engineers at

Bell Telephone Laboratories Nokia Bell Labs, originally named Bell Telephone Laboratories (1925–1984), then AT&T Bell Laboratories (1984–1996) and Bell Labs Innovations (1996–2007), is an American industrial research and scientific development company owned by mul ...

and subsequently developed into a commercial process by Ferranti in the UK.Technology Transfer and the British Microelectronics Industry, 1950-75: John F WILSON
/ref> The original ZN41x family have not been manufactured for some time, but modern equivalents to the original 3-pin ZN414 are available, with part codes of

MK484 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 ad ...

, TA7642 (different connections) and (mainly in India, the Far East & Australasia) YS414 and LMF501T. Note that on the YS414 part, pins 1 (output) and 3 (ground/earth) are transposed. Currently (2017) only the TA7642 is manufactured and is used in some AM/FM radios that use the 70 kHz IF single chip VHF-FM IC.

Performance

The upper limit of operation is about 3 MHz, so it's not suitable for a

shortwave radio Shortwave radio is radio transmission using shortwave (SW) radio frequencies. There is no official definition of the band, but the range always includes all of the high frequency band (HF), which extends from 3 to 30 MHz (100 to 10 me ...

. However, it can be used as an IF amp. The high input impedance means a valve (tube) radio IFT (IF transformer) is much more suitable than a ceramic filter or

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 e ...

IFT. Many designs using an SA612 as

local oscillator In electronics, a local oscillator (LO) is an electronic oscillator used with a mixer to change the frequency of a signal. This frequency conversion process, also called heterodyning, produces the sum and difference frequencies from the frequenc ...

/ mixer and the ZN414 / TA7642 have been published on the Internet. AGC is applied by the

resistor A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow, adjust signal levels, to divide voltages, bias active el ...

from the output to the "earthy" end of the input coil. Basic gain is set by the load resistor. The current consumption is so low that a 1.8 V red

LED A light-emitting diode (LED) is a semiconductor Electronics, device that Light#Light sources, emits light when Electric current, current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy i ...

(not the 2.2 V high efficiency types) can be used as a shunt regulator from 3 V batteries or a 5 V supply.

Notes

External links

{{commons category, ZN414
ZN414Z/415E/416E datasheet

MK484 datasheet

TA7642 datasheet

* ttp://www.zen22142.zen.co.uk/Circuits/rf/ZN414.htm Another ZN414 radiobr>A MK484 radioFerranti Electronics ZN414Z/ZN415E/ZN416E datasheet reprint by Jaycar Electronics
Ferranti Linear integrated circuits