View Index by Level
RANDOM PAGE

SITE SEARCH

LOG
IN

SIGN UP

HELP

MK484 One Chip Radio


This is the AQA version closing after June 2019. Visit the the version for Eduqas instead.

To gain access to revision questions, please sign up and log in.

Non-Exam Extras

The ZN414 is dead - long live the MK484!

The MK484 chip incorporates RF amplification, AM demodulation, AF amplification and automatic gain control (AGC).

The chip data sheet assumes you will use a 1.5 volt cell to power the radio.

This diagram also includes regeneration (not documented in the data sheet). This is positive feedback of the MK484 RF output back to the input. This compensates for energy losses in the ferrite and the tuned circuit. The feedback consists of a longish wire routed near the ferrite rod. (It is a coil with one turn.) The positioning of this wire is critical. If the coil is in the wrong orientation, the feedback will be negative. If there is too much feedback the receiver will become unstable.

The effect of regeneration is to ...

MK484-radio.gif

MK484 and ZN414 Pin Compatibility

We have replaced a ZN414 with an MK484 on one of our AlphaKit radio modules. It seems to work at least as well as the original. The pinout is different and the MK484 has to be soldered in, apparently the wrong way round. No other components were altered.

ZN414-MK484.gif

Ferrite Rod

Ferrite-rod.jpg

Ferrite-rod.gif

 

 

 

reviseOmatic V3     Contacts, ©, Cookies, Data Protection and Disclaimers Hosted at linode.com, London