The device above is MINILAB. It comprises a versatile function generator, a frequency counter, numerous power supplies, a power amplifier as well as a DVM. You will be using this device for almost all experiments. Therefore familiarity in its usage will definitely be an advantage.

Below is a brief description of the MiniLab buttons and their functions.

FUNCTION GENERATOR

  1. Range Switch : The desired frequency range is selected by depressing the correct button.
  2. Frequency Vernier Control: Uncalibrated control cover over 3 decades of frequency on each range.
  3. Digital Readout: When switch 4 is up, the readout will display the output frequency of the waveform present at the Function Generator BNC output socket. The readout in kHz or MHz is automatically selected by the Range Switch 1.
  4. Counter Source Switch : In the up position the counter displays the frequency applied to the BNC input socket 6. The correct frequency range for the externally applied frequency is selected by the Counter Range Switch 5. Frequency overload will cause the display to flash on and off.
  5. Counter Range and Frequency Divider Switch This switch controls two functions. As a counter range switch it enables the most appropriate to be selected to suit the applied input frequency. The maximum frequency that can be counted without overload is marked on each step.
    NOTE : A higher input frequency than the counter will accommodate will cause it to indicate overlod by flashing on and off but this does not affect the divider facility.
  6. Counter Input Socket (BNC) : Input socket for frequency counter or frequency divider.
  7. Symmetry Vernier Control : Fully counter clockwise the waveform remains symmetrical as it is turned one side of the waveform will be extended.
  8. Symmetry Selector Switch : In the centre position, the Function Generator ouput waveforms are symmetrical. When pushed UP or DOWN, the rising or falling waveform symmetry can be adjusted by the Symmetry Vernier Control.
  9. Sweep Frequency Control : Counter-clockwise the ramp selected by the LIN-EXT-LOG switch is at the slowest speed and fastest when fully clockwise.
  10. LIN-EXT-LOG Switch : In the centre position external signals applied to the FM input will frequency modulate the Function Generator output. A +ve voltage will increase the frequency, and a -ve voltage will decrease it.
    When LIN is selected a linear sawtooth waveform will sweep the frequency, the minimum frequency being set by the FREQUENCY VERNIER 2 the maximum by the Ramp Sweep Control and the rate of the sweep by the Ramp Frequency Control.
    When LOG is selected the operation is the same as for linear except the sweep waveform is logarithmic.
  11. Ramp Sweep Control : Sets the high frequency limit of the sweep width as described for the LIN-EXT-LOG switch. Note that as the sweep width is reduced the sweep repetition rate increases.
  12. Amplitude Control : Adjusts the output voltage over a 20:1 amplitude range. Output impedance is not affected by the level control.
  13. Frequency Generator Output Socket (BNC) : Output socket for Function Generator waveforms.
  14. 10 and 20dB Attenuator Switchs : Independent switches to select output levels. When both are depressed output is reduced 30dB. The Level Control 12 provides a further 26dB of attenuation making the total of 56dB, i.e an approx 600:1 range in output level control.
  15. Offset Control : Fully counter-clockwise and switched off, the output waveform will be centred about ground. When the control is turned, the position of the output waveform about ground is adjustable over ±10V open circuit, or ±5V into 50 ohms.
  16. Waveform Selector Switches : Both switches out, output waveform is sinusoidal. Left hand switch only pressed in, output waveform is triangular. Right hand switch only pressed, output waveform is rectangular.
  17. AM switch : In the OUT position waveform is normal, when IN the output amplitude is reduced to 50% and signals to the AM socket (input 100 kOhms and 33pF) will control the amplitude of the output waveform.

    Note: Distortion, linearity and rise time specifications do not apply to amplitude modulated waveforms.

  18. 1Hz clock output socket : A one second square wave is available from a 4.7 kOhms source impedance.
  19. f/N socket : Output at this socket is the waveform applied to Frequency Input socket, divided down by the decade ratio selected by the Frequency Divider switch. The output is a square wave for any division ration and a clipped off version of the input waveform in the /1 position. 4.7 kOhms source impedance.
  20. AM socket : Signals applied to this socket will amplitude modulate the Function Generator waveforms when the AM selector switch is depressed. A positive voltage will increase amplitude, negative will decrease it. Approx 3Vp-p is required to provide 100% amplitude modulation. Input impedance is 100 kOhms and 33pF nominally.
  21. FM socket : Signals applied to this socket will modulate or change the frequency when the LIN-EXT-LOG switch is in the centre EXT position. A positive voltage will increase the frequency, a negative will decrease it.
  22. _|_ Socket : Ground terminal for input or output waveforms.
  23. SYNC socket : A positive going signal of 0 to 3V approx from a 4.7 kOhms source. The signal is 180º out of phase to the main output waveform.
  24. RAMP Gate Pulse : A positive going 0 to +6V pulse from a 10 kOhms source is available during the return sweep period of the internal ramp to provide an oscilloscope trigger and CRT blanking pulse.
POWER AMPLIFIER/BIPOLAR POWER SUPPLY
  1. Selector Switches : With all switches out the Function Generator output is connected to the amplifier. With the Gain/Voltage control fully counter clockwise the same amplitude signal will appear at the Amplifier output terminals as its present at the Function Generator BNC output socket. When the INT-EXT button is pressed, external signals can be applied to the amplifier via the Amplifier Input terminals. The centre button inverts the output providing for example the Function Generator with a push pull output.
    The R.H. switch changes the circuit from a power amplifier to a Bi-Polar Power Supply. When it is engaged the Gain/Voltage control adjusts the output voltage from -15 to +15V.
  2. Gain/Voltage Control : When the Power Amplifier is selected this controls adjusts the gain from ×1 to ×100. When the Bi-Polar power supply is selected it adjusts the output voltage from -15V to +15V. The power amplifier can be used as a voltage programmed power supply over the range -15V to +15V. The gain control adjusts the programming voltage from ± 15V at minimum gain to ±150mV at maximum gain.
  3. Amplifier Input Terminals : Input connections to power amplifier. Input in 100 kOhms and 20pF nominally.
  4. Amplifier Output Terminals : Output terminals for Power Amplifier or Bi-Polar power supply as selected by the Selector switches.
  5. 0 to -15V Control : Adjust the negative half of the isolated power supply from 0 to -15V at 1 amp.
  6. 0 to -15V Terminal : Output connection for -ve power supply.
  7. Common and Ground Terminal : When the two terminals are linked the positive and negative output voltages are with respect to ground. Witht the common terminal isolated, it or the positive or negative terminals can be connected to any other supply up to ±100V with respect to ground.
  8. 0 to +15V Control : Adjust the positive half of the isolated power supply from 0 to +15V max at 1 amp.
  9. 0 to +15V Terminal : Output connection for positive power supply.
  10. 5V, 3Amp Output Terminals
DIGITAL METER
  1. V/A-Ohms Selector Switch : Volts or Amps can be measured with the switch out (V/A). Ohms are measured when the switch is in (ohms)
  2. DC-AC Selector : DC volts or amps are selected with the switch out and AC Volts or amps (true rms) when in.
  3. Range Switches : Push buttons to select the voltage, current or ohms ranges.
  4. V or Ohms Input Socket : AC and DC voltages or ohms are applied to this input socket.
  5. Common Socket : Input for the low impedance side of all measurements. Socket is isolated from ground and may be taken to a maximum of + or -500V DC from ground.
  6. Amps Socket : Input for AC or DC current measurement.
  7. Digital Meter Readout : 3½ digit readout with + or - indication for DC volts or amps. Polarity indication is automatic and overload is indicated by a 1 on the MSD and the ramaining digits blanked.
  8. Power ON-OFF : Illuminated rocker switch, switches both active and neutral input AC lines to the power transformer.

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