Projects in the July 1998 issue of EPE Magazine

PIC16x84 Toolkit - EPE's original design for PIC16C84 and PIC16F84 microcontrollers. Stand-alone or interface to the PIC Tutor board, the PIC Toolkit was designed for speed and versatility. At last, TASM and MPASM compatibility! The EPE PIC Toolkit is a programmer, program disassembler and bi-lingual translator all in one - a great idea for PIC users everywhere! Translate between TASM and MPASM using easy DOS-based options. You need a PC-compatible computer with QBasic or QuickBASIC installed, and a parallel port. A 12-14V d.c. power supply is also required, which can be derived from an expansion socket or separately.

The original PIC Toolkit is now obsolete and you should use the TK3 (Toolkit Mk3) - October 2001 issue.

In the September 98 issue (P. 685) we advised that on Page 527, Fig 1 l.e.d. D1 is shown the wrong way round. The cathode (k) should go to the +5V line. The p.c.b. layout is correct. In Fig. 3 and Fig 4, the annotations for resistors R10 and R11 have been transposed. R10 is the one that joins resistor R9. Both resistors have the same value (100k). Also, in Fig. 3 and 4, resistor R6 is shown as R3 connected to the base (b) of transistor TR3. R3 is the one that goes to pin 1 of IC3. In the January 1999 issue (P. 34) we commented that QuickBASIC/ QBASIC memory capacity can be exceeded in some situations of the conversion/ disassembly routines. The program has been slightly rewritten to overcome these problems, and the source code files (diskette/ FTP site) updated. Also, all references to the Busy line should read as Acknowledge line. In Fig. 5 the connection marked Busy should go to the printer port connector pin 10, not 11 as shown. The software, p.c.b. and standard printed cable connections are correct.


Greenhouse Computer (Part 1)
- microcontroller design uses Atmel's AT89C2051. Monitors and controls heating and watering for your glasshouse. Part 2 includes a radio link, which uses DTI-approved 418MHz radio modules.

In the January 1999 issue (P. 34), we said that under certain circumstances a small d.c. voltage can occur across the probes which may affect the readings. To avoid the problem, amend the Controller p.c.b. as follows: change C14 to 10nF, C13 to 470nF (0µ47), add a 100k resistor in parallel with the probes across TB3. Add a 470nF (0µ47) capacitor in series with TB3 pin 2 and its probe. The software (diskette/ FTP site) has been updated to reduce the default watering time.

Using the L200CV voltage regulator - Andy Flind outlines basic principles of this versatile device.

Noise Cancelling Unit
Robert Penfold's novel anti-phasing design will, with a reasonably high quality set of headphones and microphones, provide a reasonable degree of attenuation over the low-mid audio spectrum. Stripboard design.

Low Battery Indicator
- high performance, micropower circuit won't load your projects unduly. Compact design fits most d.c. projects. Easy stripboard project