Electronics Workshop

Development of Electronic devices

Time of Flight Data Acquisition System

Some physical experiments (e.g. mass spectrometry) have a need to count the number of pulses per time frame. The device which was developed at our institute is furthermore capable of communicating with stepper-motors, a temperature regulator, a voltage measuring board and a quadrupole.

All these features are combined in a single device:

A Matlab program (running under LINUX) commands the TOF device via a standard RS232 interface. The modules inside the device are talking on a 2^nd RS232 line.

BAL_TOF1:
This slave module can be considered as the core of the whole device, as it provides the time framed counting of the incoming
pulses. Some Verilog code was implemented on a FPGA, in order to provide the following features:

up to 2046 time frames (user setable)
time per frame: 0.5 µs - 12.0 µs (user setable)
programmable pre - delay (until counting starts)
start / stop counting
reset counters
read the value of one or all time frame(s)

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Gated Photon Counter

Features:

2 / 4 channels
Chopper controlled
200 ms / 1 s integration time
RS-232 output
ECL pulse input
5 / 10 / 20 ms gate time

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Handheld, battery powered Data Logger

Data Logger for Analog Voltages

With this handheld, battery powered device the user can easily measure voltages in the range of ±2 V and log the data to a compact flash card.

The resolution is 14Bit (1 LSB equals to 250µV).
The sampling frequency is selectable and can be up to 1 MHz.

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Counter for Students Lab

The incoming pulses are counted and displayed as

counts / s
total counts

The data can also be acquired via a RS-232 port - either in the auto-output mode or in the polling mode.

A pushbutton or a command from the serial port resets the counter.

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5 Channel Heating Box

Each channel can provide up to 1000 W heating power! The desired temperature can be set from 50 °C to 200 °C. The actual temperature is measured by a standard type K thermocouple.

230 V (european) outlets are used to connect the high-voltage heating elements.

The regulation is controlled by a microprocessor. The power section is opto-isolated from the controll-stage.

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Pyrometer & Photodiode Amplifier

Most photodiodes have a current output. In order to make this generated signal more handy special amplifier circuits (transimpedance amplifiers) are needed.
To avoid ringing, to achieve a good signal to noise ratio and to get the desired signal amplitude the amplifier must be matched with the photodiode used. Therefore no run of the mill amplifier can be used or must at least be modified.

Many photodiode amplifiers have already been developed at our institute. Some have a high gain, others also control the peltier cooling of the diode.

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Two-Wire to RS-232 Converter

When you look for a quick way to test 2-wire slave ICs your search has come to an end.

Simply use a standard RS-232 terminal program, send ASCII commands to this device and you have got a 2-wire Master!

This portable device can be powered by either 4 AA battery cells, or by an external power supply.

The voltage for the 2-wire interface can be 3.3 V or 5 V and the baudrate of the RS-232 is also selectable.

The logic level of 2 BNC connectors can be programmed in order to generate test pulses. Furthermore you can insert time delays, which may also be helpful when exploring a new chip.

Programmable pull-up resistors and clock speed complete the functionality of this handheld unit.

Manual and technical documentation

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Universal Counter

Some experiments call for accurate time measuring.

Say you want to calcute the earth's acceleration by measuring the time of a free falling body and you are showing the experiment in an ample lecture hall. Then you need a counter with big digits.

The all-purpose counter developed by M. Hafner at our institute has the following features:

TTL input for Start/Stop and Reset
Keys for Start/Stop and Reset
Counts up to 100 seconds in 100 µs steps
Several auxiliary voltages (for additional circuits) are available on the front panel

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RS-232 Converter

Have you ever been in the enervating situation that you had to connect a device via its RS-232 interface, but you could not match the interface parameters?

Here we present a device which overcomes this pain:

The RS232 parameters of each side can individually be set. A buffer ensures that bytes, received at a higher baudrate than sent out, are not lost.

Features:

Baud rates from 300 to 115K2
all parities
7,8 or 9 data bits
1, 1.5 or 2 stop bit(s)
delayed, setable transmitting (0 µs to 10 s)

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Scan Generator

Scan Generator analog

The main aim of a scan generator is to provide a accuratee, linear sweep voltage. In most cases a triangular or sawtooth wave form is used. The generated voltage ramp can then control other device, such as laser control boxes or deflection systems.

Features:

Many operating modes
Adjustable scan time (rough and vernier)
Setable scan width with offset

Scan Generator digital

Features:

Terminal or PC software controlled
LEDs for Mode
Analog display

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USB Terminal Program for the FT245R chip

Are you already using FTDI's FT245R chip to establish a simple connection between your microcontroller (or CPLD, FPGA) target board and your personal computer?
Then you will also desire a terminal program for your PC, which works similiar to Hyperterminal or other RS-232 terminal programs:

FT245R_Term is a first try to bridge the gap.

Features:

ASCII and HEX
Monitor Windows
Save or print the content of the monitor
Versatile EOL termination (CR, LF, NONE,...)

The project was done in C# (.NET application) under the SharpDevelop Enviroment.

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