ZN414
Encyclopedia
The ZN414 was a low cost, single-chip AM radio integrated circuit
. Launched in 1972, the part was designed and supplied by Ferranti
, but was also available 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
'transistor' package whereas the GEC part and later Ferranti ones (ZN414Z) used the plastic TO-92 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 was based on a design known as Tuned Radio Frequency
(TRF). The TRF design is much simpler than the popular, but more complex, superheterodyne radio circuit often used in modern AM receivers. It was principally the use of the TRF circuit that allowed 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 (CDI). CDI was invented by engineers at Bell Telephone Laboratories and subsequently developed into a commercial process by Ferranti in the UK.
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
, TA7642 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.
Integrated circuit
An integrated circuit or monolithic integrated circuit is an electronic circuit manufactured by the patterned diffusion of trace elements into the surface of a thin substrate of semiconductor material...
. Launched in 1972, the part was designed and supplied by Ferranti
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. Known primarily for defence electronics, the Company was once a constituent of the FTSE 100 Index but ceased trading in 1993.The...
, but was also available from GEC-Plessey. The ZN414 was popular amongst hobbyists as a fully working AM
Amplitude modulation
Amplitude modulation is a technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. AM works by varying the strength of the transmitted signal in relation to the information being sent...
radio could be made with just a few external components, a crystal earpiece
Crystal earpiece
A crystal earpiece, more properly called a piezoelectric earphone, is an earphone that produces sound by using a piezoelectric crystal, a material that changes its shape when electricity is applied to it...
and a 1.5 V cell.
The original ZN414 chip from Ferranti was supplied in a 3-pin, metal TO-18
TO-18
In electronics, TO-18 is a designation for a style of transistor metal case. The case is made of metal and is therefore more expensive than the similarly sized plastic TO-92 package used for other transistors. The name is from JEDEC, signifying Transistor Outline Package, Case Style...
'transistor' package whereas the GEC part and later Ferranti ones (ZN414Z) used the plastic TO-92 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 was based on a design known as Tuned Radio Frequency
Tuned radio frequency receiver
A tuned radio frequency receiver is a radio receiver that is usually composed of several tuned radio frequency amplifiers followed by circuits to detect and amplify the audio signal. Prevalent in the early 20th century, it can be difficult to operate because each stage must be individually tuned...
(TRF). The TRF design is much simpler than the popular, but more complex, superheterodyne radio circuit often used in modern AM receivers. It was principally the use of the TRF circuit that allowed 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 (CDI). CDI was invented by engineers at Bell Telephone Laboratories and subsequently developed into a commercial process by Ferranti in the UK.
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
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 signal transistor. It replaces the similar ZN414 AM radio IC from the 1970s. The MK484 is favored by many hobbyists...
, TA7642 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.