Introduction: Redesigned Radio Clock
Step 1: Problems With the Clock
I bought a radio clock produced by Scott. ( http://www.audioscott.com ) .
The visual design is not bad, but the quality was terrible. (something usual for products "Made in China")
The clock was not going, some segments of the LED display were not working.
I opened it to see what is the reason, breaking up the warranty.
First observations:
1) the PCB of the LED display was curved and the contacts to the between corresponding pads on the PCB and the LED display were bad
2) For the clock the LM8560 chip was used, which doesn't use a quartz generator, but is synchronized with the frequency of the AC power net (can be chosen 50 or 60 Hz) - that means bad time accuracy.
3) The PCB of the clock is done with extremely bad quality - it is impossibly practically to solder something on it without destroying the soldering pad or the corresponding track - they simply fall down from the PCB.
4) The flat cables used there were something exceptional - it was possible to split and strip them only by fingers.
5) In the clock was used a Chinese analog of the TA2003 AM/FM radio chip, but only the FM option was used, because it doesn't need ferrite antenna.
My attempt to repair the clock failed - it was not working. The only functioning thing was the FM radio. I decided to use the clock only as radio, but to make it more interesting and attractive. So, I decided to mount inside the clock a small LED light organ on the place of the digital clock display.
Step 2: Redesign Idea
For that purpose I removed the display. I removed also the clock chip to reduce the consumption and cut all cables used for the clock.
I found in Internet the following schematics for LED light organ ( http://www.b-kainka.de/bastel85.htm ). It has microphone preamplifier which in my case was not needed - the radio has built in audio speaker amplifier.
I used only the marked part of the schematics.
Step 3: The Light Organ Design
I developed a small PCB which can be inserted inside the clock. ( How to do this can be seen here:
http://www.riccibitti.com/pcb/pcb.htm
or
https://www.instructables.com/id/5pcb/ ). In this case no mirroring of the picture is needed, because there is not any chip used.
The dimensions of the PCB are : 25 mm x 25 mm ( 1inch x 1 inch). They can be reached by proper scaling during printing of the PDF.
Attachments
Step 4: Needed Parts
The list of the pats is:
3 transistors NPN 2N3904 (can be used each small signal NPN with BETA>80)
3 small signal diodes ( I used Schottky diodes from the type 1N5711, but can be used a normal Si diode)
3 Resistors 200 Ohm ( for 5V supply) - in series with the LEDs
3 Resistors 10 KOhm
1 x 2.2uF electrolyte capacitor
1x100nF ceramic capacitor
1x22nF ceramic capacitor
1x10nF ceramic capacitor
1x4.7nF ceramic capacitor
3 Bright LEDs - red, green, blue (can be put more in series, but must be taken in mind the used supply voltage)
3 suitable LED reflectors (#250807 at Distrelec)
Step 5: Assembled Light Organ
I put the light organ PCB in the clock, under the display windows and fixed it with hot glue gun. The ground cable of the PCB I connected to the common ground of the clock. The supply cable I soldered in the place where the supply of the missing now clock chip was connected. The input of the light organ was soldered to the speaker wire.
Step 6: The Project Is Ready
If the device is correctly assembled and connected it works nice and without problems.
Of course it can be mounted in each type of radio, where a supply voltages from 4.5 to 20 V are available. If you want to use it for iPod, MP3 player&etc - then, you have to include also the preamplifier part of the schematics, because the signal level for the phones is not enough to trigger the device. You can place the device also in separate box, to use a plenty of serial/parallel connected LED's - this depends only on your skills and imagination.
