November 2006

how to convert old orcad sch pcb to win32 orcad formats

• install msdos orcad esp 4.2 with sdt 4.13 and pcb 2.2 or versions close.
• install win32 year 99-2k orcad or demo or student edition from win98.
• in capture open sch sdt file and it will convert if old dos sdt libraries exist.
• in old orcad pcb plot pcb layer to dxf file, in win32 orcad layout import dxf .
• in layout print layer as black-white to hp-adobe postscript driver to file ps.
• open ps file with ghostview and convert to pdf and print it or store it.

you need win98 to do all this. but you have xp make dual boot with both win98 and xp, take the help of a computer expert or you may end up crashing xp. you are still unable to convert take the help of a software person. the later versions of orcad may not open these files.

This is a RTD Pt-100 Transmitter, It can Convert Thermocouple mV or RTD mV to 4-20 mA Current Transmitter. The part numbers on Circuit and silk screen may not match. But the PCB may be usable. The output is a current source and not a current sink. It goes to a 4-20mA Mux with a common ground. The Circuit RTD-Pt-100-Transmitter Circuit

The PNGs of PCB is 600dpi 16 color. It is to be scaled appropriately.

• trxdt.png Drill Template
• trxl1.png Copper Side
• trxss.png Silk Screen
• trxsm.png Solder Mask

zoom image

These are the circuits and boards of a Mini Temperature Transmitter for a Platinum hundred ohms temperature Sensor.
RTD-3W-Transmitter Circuit. See my Transmitter Application Note for this.

The customer wanted a two wire system, this needs low power opamps which were ten times the price. If this transmitter works at 3mA it could have been two wire. Those parts were in short supply and the budget of customer was low. So i made it with regular opamps but three wire. The customer was satisfied as he got a cost effective solution. But now the situation of markets and products are different.

If you need to transmit the temperature from a high voltage area or toxic environment. You will need to hermetically seal the transmitters, convert the Voltage to frequency, frequency to IR LED flashes or RF. This can be then remotely monitored. Then the transmitter has to be battery-solar operated, low power too. ICL7135 is a simple solution. It has a serial output that can be used to Drive IR Leds. Remotely sense these flashes in a Micro-controller and you have a reading. You may be able to use optic-fibers too. Where volatile liquids are present so that the risks of sparks can be eliminated.

The PNGs of PCB is 600dpi 16 color. It is to be scaled appropriately.

• trxmindt.png Drill Template
• trxminl1.png Copper Side
• trxminl2.png Component Side
• trxminss.png Silk Screen
• trxminsm.png Solder Mask