Friday, February 16, 2018

Home made DIY - How to make auto scan radio on breadboard

This is my first home made DIY auto scan radio. Yes -- usually small radio are based on analog with the coil antenna which is difficult to wind to a specific band. This radio circuit is only depend on one central micro chip BK1079 and in fact this is just a prototype and it works quite well on a breadboard.

The Good auto-scan radio.

It does not require specific antenna winding like the analog radio - which reduces the experimental job on the antenna. It depends on the processing frequency within the micro-chip as long as the radio signal are within reach it can detect all the FM frequencies in range just with push of seek button.

Component Required for building the Auto-scan radio

1 x BK1079 radio chip
1 x 100 nH - inductor
1 x 18 pF ceramic capacitor
1 x 100 nF ceramic capacitor
1 x 10 uF electrolyte capacitor
3 x 10 kOhm resistors
3 x push button (reset, seek, and volume)
1 x antenna (simple)
2 x AA Batteries (3 volt DC)

How to make

Step 1: Convert BK1079 SMD to use Through Hole pin using MSOP-10 board adapter

Firstly I am working on through board / breadboard and the BK1079 is a SMD (surface mount device) mount. We need an adapter board which convert the BK1079 to use for through hole board purposes with pin package MSOP-10. In this case i don't have MSOP-10 but i can still use alternative board MSOP-16 which has more pins.

The soldering process require some experience since the pin are very tiny and close to one another. One thing you have to avoid is the bridging join during soldering.

Step 2: The components assembly

The assembly on breadboard seems to be easy since it is just plug into the holes. However bear in mind that anything to do with frequency transmission require very solid connection. So you don't want any loose connection otherwise the radio signal will fail or too much noise later on. Find breadboard cable jumper that snug fit into the board holes. This is to prevent noise or failed frequency signal.

Then assemble the component based on this simple schematic diagram below.

The antenna is optional - because it does not bring so much different to signal received based on my experiment. The micro-chip is so special that it can receive signal quite clear even without an antenna but perhaps just get one or a piece of wire as antenna just to make sure everything are in place. However if you have germanium diode as the antenna that would be the best because it can capture all range of radio frequencies from MF (Medium Frequency), HF (High Frequency), VHF (Very High Frequency), and UHF (Ultra High Frequency) which means from normal radio signals up to ultra-high mobile phone signal such as 4G LTE.

It is advisable to solder the push button on permanent circuit board because putting it on the breadboard would be too shaky and it will fail the circuit. So by soldering on permanent board it's placement is rock solid.

Step 3: Testing the output

Try not to use higher voltage to avoid burning the circuit - so use the specified voltage using 2 AA batterys (3 volt). Secondly try to get the speaker a little longer cable so that you can put a little bit further than the circuit during testing. Because if you the speaker is too close it could disrupt the signal and produce great noise than usual. Good luck with your project.