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DonTronics - DT003

Dontronics - DT003 Simmstick Power Supply and Comms Platform.

Is a Simmstick Power Supply, Communications Port using a Max-232, and a 4 slot Simmstick Bus and bus extender done on a double sided, plated through, solder masked, silk screened 1.2mm PCB.

The larger DT001 is great for a development platform and programmer, however the price really limits it to this function. You wouldn't really use it in an end product unless the product was giving you an excellent return.

I have come up with a DT003 which is a shorter version DT001 (2.675" long, same width) that has a power supply, D-9 connector, Max-232, reset and boot buttons, 4 SIMM sockets, and expansion connector on the right hand end, same as DT001. This isn't a programmer board, but a support board for Simmstick, at a much reduced rate compared to the DT001 board.

DT003 isn't a programmer. It's ideal as an end User platform for chips that have already been programmed such as FED, Parallax, or any other Basic Interpreter chips, or any Simmstick that requires just a power supply or a Comms port and a small Simmstick bus structure.

Download Schematic in PDF format.

Board Components:

1 by DT003 PCB

1 by 7805 +5 Voltage regulator in TO-220 case.                        DT
1 by Suitable heat sink for above Regulator.                          DT
1 by Diode Bridge D1 WO2 (or WO4 type)                                DT
1 by 2.1mm (or 2.5mm) DC Input plug. PCB mount.                       DT
Provision is also made for screw terminals at .2" centers.

1 by Capacitor C1 1000uf Electrolytic @25 Volts. (PCB type mount.) Provision is made to fit larger caps if required. This can be caps with .3", .4", or .5" centers, or 1000uf, 2200uf or 4700uf, however you may experience problems with the largest diameter capacitor (4,700uf) on this board if you require the Comms components. In most cases, the 1000UF cap is fine.

1 by Capacitor C2 .01uf (or .1uf) Ceramic
1 by Capacitor C3 .01uf (or .1uf) Ceramic
1 by Capacitor C4 10uf Electrolytic (PCB mount.) or Tant. @16 V.
1 by Resistor  R1 330 .25 watt Green LED 1 (+5V)
1 by 5mm Red LED. LED 1 +5V monitor
4 by 12mm square .5" stick on rubber feet. Adds a nice finish.        DT

Serial Communications:
1 by Capacitor C5 1uf Electrolytic (PCB mount.) or Tant. @16 V.
1 by Capacitor C6 1uf Electrolytic (PCB mount.) or Tant. @16 V.
1 by Capacitor C7 1uf Electrolytic (PCB mount.) or Tant. @16 V.
1 by Capacitor C8 1uf Electrolytic (PCB mount.) or Tant. @16 V.
1 by MAX-232 E2 (or equivalent)                                       DT
1 by D-9 right angle PCB mount connector.                             DT

It may also pay to install a 16 pin socket for the Max-232, as you may have to remove it for some configurations.

The unused pins of the Max-232 have been brought out to pads. The RS-232 signal level pads can be found near the D-9 connector pins on the solder side of the board. The TTL levels are found at header J1. Pin 1 is input, and pin 2 output.

RESET and BOOT Switches:
A Reset can be added for CPU control, and I have also included a BOOT switch on the SDA signal. If a pull-up resistor is fitted on a Simmstick module, then this line can be used as a single line switch input. I added it mainly for FED Basic COMMS control.

1 by Resistor     R2 330  .25 watt Boot Button.
1 by Resistor     R3 330  .25 watt Reset Button.
2 by Suitable switches.                                  

These can be the pretty plastic colour ones that have .2" centers, or the mini 4 pin TACT switches that have a .2" by .3" pattern.

J2 is shown as a 30 pin female right angle header. This can be used to extend the Simmstick bus to other boards.

Circuit diagram for DT003

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Last modified: February 24, 2024