DCF77 clock with SAB0600 gong

It is recommend to build the DCF77 clock with the SAE800.
The SAE800 is the successor from the SAB0600, SAB0601 and SAB0602 together.
But for those who have at home an old SAB0600, SAB0601 or SAB0602 in stock is here a special scheme and program.

The SAB0600 is a triple tone soundgenerator, the SAB0601 a single tone and the SAB0602 a dual tone.
The successor SAE800 can produce single, dual as well as triple tone gong sound.

Now there is something unpleasant with the SAB0600.
This 8-pins sound-IC needs namely a power supply from 7...11V, so 5V is to low.
It is possible to take the power before the voltageregulator 7805, but only when this voltage isn't higher than 11V (see scheme 1)

Scheme 1

Another possibility is to build a charge pump, which makes a higher voltage from out the 5V.
Herefore comes on PORTA.6 (pin 15) during the gong for 15 seconds a frequency from 10kHz, to generate from this a higher voltage (see scheme 2).

Scheme 2

Adjust with P2 the pitch from the gong and with P3 the volume.
It is to be recommended to set the volume in scheme 2 not to the maximum, seen that the charge pump can't give enough current then, the voltage comes under 7V and that's not good for the sound quality.
To activate the gong connect the SAB0600 with PORTA.1 (pin 18) from the PIC.
This pin gives every half- and whole hour a short pulse.
It's also possible to let the gong sound only the whole hours, therefore must PORTB.1 (pin 7) connect to GND, normally just let this pin open (internal pull-up).
A speaker from an old transistorradio for example is fine as long as it has an impedance from 8Ω.
Use for the LCD a HD44780 (or compatible) with 2x16 characters.
If you build the DCF77 project with the SAB0600 then it is recommend to read also the part from the SAE800.
This program does in contrast to the program for the SAE800 not use the DCF77 paritybits.

Download DCFSABUK.HEX, V-1 file to program in a 16F628(A)
Download DCF77_SAB_V-1_UK.bas, the sourcecode voor PIC Basic
The working from the DCF77 time signal
www.ptb.de Check your DCF77 clock till the last second
Datasheet SAB0600.pdf, SAB0601.pdf, SAB0602.pdf
Datasheet HD44780 LCD (Liquid Crystal Display)