PC Boardsfor most Silicon Chip (plus EA & ETI) projects can be obtained from RCS Radio, Sydney.
Phone (02) 9738 0330. Fax (02) 9738 0334. Email sales@rcsradio.com.au or visit www.rcsradio.com.au

Simple Ultrasonic Proximity Detector (Car Reversing Alarm), January 1989:
D1, as shown on the wiring diagram of page 28, is reverse connected. The circuit diagram on page 27 is correct.

Narrowband FM Receiver, February, March 1989:
the unused secondary winding of the quadrature coil L2 is shorted out by the underside ground plane of the printed circuit board, as shown in Fig.2 on page 70 of the March issue.

This causes a loss of sensitivity. The cure is to remove the coil and then use a small diameter drill to remove the copper away from one of the unused pins of the coil. The coil can then be soldered back into place.

Stereo Compressor for CD Players, March 1989:
the two 470μF electrolytic capacitors used in the power supply are shown reversed on the wiring diagram (Fig.4). The circuit diagram (Fig.3) is correct.

Studio Series 32-band 1/3-Octave Equaliser, March, April 1989:
one of the four 220μF electrolytic capacitors shown on the main equaliser in the wiring diagram (Fig.1(b) on page 48 of the April issue) is reversed in polarity. The capacitor in question is connected to pin 4 of IC2.

Lotto Selector, May 1989:
the .012μF and .018μF capacitors listed in the parts list should be 0.12μF and 0.18μF respectively.

Touch Lamp Dimmer, June 1989:
As noted in the article, the revised version of the SLB0586 does not require diodes D1 and D2 but they will not affect circuit operation if they are left in. However, now that the revised chip has been released, as SLB0586A, it has been found not to work in the circuit as published. To make it work, two components must be changed.

The 680k resistor must be swapped for a 0.33μF capacitor while the .0022μF capacitor should be swapped for a 100k resistor. These components will fit without any modifications to the PCB pattern being required. If your kit has the original SLB0586 IC, no circuit changes are necessary.

Extension for the Touch-Lamp Dimmer, July 1989:
the wiring diagram, Fig.2, on page 33 is incorrect. It shows the Active connection and the Extension connection transposed on the insulated terminal block. This mistake is repeated on the Dimmer extension board shown on Fig.3 on page 35.

Ultrasonic Car Burglar Alarm, July 1989:
the wiring diagram on page 63 shows one side of the siren connected to chassis. It should connect to +12V, as shown on the circuit on page 61.

Garbage Reminder, August 1989:
the .047μF supply bypass capacitor shown between IC6 and IC7 on the wiring diagram of page 50 is shown as 0.1μF on the circuit of page 49. The value is not critical though and either 0.1μF or .047μF is OK.

Alarm-Triggered Telephone Dialler, September 1989:
the alarm input polarities are shown transposed on both Fig.2 (page 30) and Fig.3 (page 33). The circuit diagram (Fig.1) is correct.

2-Chip AM Stereo Radio, October 1989:
on page 61, the text regarding the selection of the two .047μF 2% capacitors should read “.046μF to .048μF”. Also, the artwork on page 66 showing the Sydney radio stations has a small error: the marking for 2FC is 10kHz too high. If you have already made up a Dynamark (Scotchcal) label, the black line can be removed by scrubbing firmly with a cotton bud moistened with methylated spirits. There is no need to remove the 2FC call sign. A new line can be added using Letraset, or microthin black artwork tape. It should line up with 576kHz on the dial instead of 586kHz. Once this is done, it should be possible to align all the dial markings to within less than half a line thickness.

Radfax Decoder, November 1989:
on page 22 the 100μF capacitor at the output of the regulator is shown with reversed polarity on the overlay diagram.

Simple 40-Metre Receiver, December 1989:
identical PCB codes were inadvertently allocated to this project and to the FM Radio Intercom for Motorbikes (October, November 1989). To avoid confusion, a new code has been allocated to the 40-Metre Receiver PC board as follows: SC06112891.

UHF Remote Switch, December 1989(and August 1990): in some cases, the MC145028 decoder (IC2) may not operate correctly since the specified oscillator components cause it to operate at 770Hz which is outside its recommended frequency range of 1kHz to 400kHz. The solution is to change the timing components so that the oscillators operate at about 2kHz.

For IC1 in the transmitter, replace the resistors at pins 11 and 13 with 220k and 100k resistors respectively and change the .01μF ceramic capacitor at pin 12 to a .0022μF polyester type. For IC2 in the receiver, change the resistors at pins 7 and 10 to 39k and 180k respectively. The capacitors at pins 7 and 10 are unchanged.