Portable DMX Tester

It is frequently necessary that a DMX-compatible device or a complete DMX installation has to be tested when faults have occurred while it is in use. With the tester described here we avoid the need to have to take over the DMX master (PC or console) for this purpose. This tester can be used in every situation, thanks to its handy size and built-in rechargeable battery. And as an added benefit, this circuit can also send and receive DMX data.Anyone who has ever installed or built DMXcompatible equipment has, in all likelihood, experienced problems when it came to the operation thereof.It is impossible to describe the wide variety of possible faults and their symptoms here, because of the enormous scale of the subject! Depending on circumstances, it is possible that a simple piece of equipment (scanner, dimmer, etc.) doesn’t respond to a command, or that a complete installation has suddenly gone haywire and is carrying out programs that only it seems to be familiar with…

Resistors:
R1 = *
R2 = 47kOhm 
R3 = 470kOhm 
R4 = 10kOhm 
R5,R6 = 4kOhm 7
P1 = 10kOhm preset
Capacitors:
C1,C2 = 33pF
C3 = 1µ F 16V
C4 = 100µ F 16V
C5-C9 = 100nF
Semiconductors:
D1,D3 = 1N4001
D2 = 1N4148
T1 = BC547
IC1 = AT90S8515, programmed, order code 010203-41
IC2 = LTC490-CN8 (Linear Technology)
IC3 = 7805
Miscellaneous:
S1-S5 = pushbutton, 1 make contact
S6 = single-pole changeover switch with centre-off position
X1 = 8MHz quartz crystal
K1 = socket, 1 row of 14 contacts (+14-way header for display)
K2 = 10-way pinheader
LCD, 1 line of 16 characters, HD44780 compatible, e.g. NLC-16x1x07 (Conrad Electronics #183 261)
Optional:
5- way XLR socket, chassis mount
5-way XLR plug, chassis mount
PCB, order code 010203-1 (see Readers Services pages)
Floppy disk, source and hex-code files, order code 010203-11
* = see text