The TM500 system is great because it has many useful stand-alone plugins available and most can be had for a very affordable price. Keep in mind that most of these plugins were made in the 70's but they still work great! There are no microcontrollers in them, just 74 series logic chips and a few custom chips.
The DC502 is a frequency counter that can count up to 550Mhz. It can display 7 digits and has a maximum resolution of 0.1hz using the direct input. The direct input accepts up to 110Mhz at 1M with up to 50x attenuation and the prescale input accepts up to 550Mhz at 50ohms with a maximum resolution of 1hz. This one has Option 1 which has the crystal oven oscillator to provide higher accuracy.
The DC508A is a frequency counter that can count up to 1.3Ghz. It can display 9 digits and has a maximum resolution of 0.1hz using the direct input. The direct input accepts up to 100Mhz at 50 or 1M with up to 10x attenuation and the prescale input accepts up to 1.3Ghz at 50ohms with a maximum resolution of 1hz. This one also has the crystal oven oscillator to provide higher accuracy. When measuring frequencies between 10hz-25Khz, there is a 100x multiplier that will extend the resolution to 0.001hz. The only problem with this plugin is that two of the digits have segments that are burnt out but other than that it works great.
The DM501 is a digital multimeter that can measure ohms, DC, AC, DC current and AC current. It can display 4.5 digits which is one more than my modern Fluke meter! The third and fourth photo below is actually another one that does not work correctly. I couldn't fix it so naturally I had to convert it to a clock! I used an ATmega168 microprocessor programmed with the Arduino language (C++) along with a battery backed DS1307 real time clock. It also shows the date every 30 seconds.
The FG503 is a function generator that can provide frequencies ranging from 0.1hz to 3Mhz, 0-20v peak to peak and can output square, triangle and sine wave shapes. When I received this plugin it didn't work but I found that just lowering the plugin's +20v supply to +19.5 causes it to work! I'm still not sure why this is.
The PS503A is a triple power supply that provides two variable supplies from 0-20v and 0-400ma (1A on a high power slot). The other supply is a fixed 5v at >1A. The two variable supplies could be used to provide a single 0-40v supply at 400ma.
The SG502 is an oscillator that provides low distortion sine waves with frequencies from 5hz to 500Khz. It can provide up to 15v peak to peak for the sine waves and fixed 5v for the square wave output. The output could also be attenuated up to 70db.
The SG503 is a leveled sine wave generator that provides a variable, constant amplitude sine wave that is adjustable from 250Khz to 250Mhz. As far as I know, it is only used to determine the vertical bandwidth of an oscilloscope.
The TG501 is a time mark generator that provides vertical markers at calibrated times. The time markers range from 5 seconds to 1 nanosecond! It's mainly used to calibrate the time base on scopes. Just set the generator for the same time as on the scope and line up the markers with the graticule. If they don't line up, then there is a timing error on the scope (assuming the plugin is calibrated). The percent error can be found by rotating the red knob (middle) until the markers line up, the error is displayed and can be checked against the allowed error shown in the scope's manual.
The TM503 is a power supply which accepts up to 3 plugins. There are other power supplies available that can hold 1-6 plugins.
Last Updated May 2010
Contact: Tai Oliphant
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