Model 122 M is ideal for experiments requiring a high voltage. It is particularly suitable for operating Sigmatron’s Cathode Ray Tube Model ST-121, the Millikan apparatus and the electrophoresis experiment.

Fully featured, this high voltage power supply is easy to operate and incorporates sophisticated safety features that:

make it easy to use

ensure a stable and precise output voltage

provide the necessary currents and voltages

make it safe and “student-proof”.

STABILITY

Model 122 M’s output voltage varies less than 1% for variations from 0 to the maximum output current (25 mA).

This figure even drops at less than 0.5 % for variations from 110 to 130 volts in the input voltage.

PRECISION

Model 122 M is equipped with a digital voltmeter and linear voltage selector that allow the user to adjust the output voltage to any value between 48 and 350 volts DC.

SECURITY

The unit incorporates a protection circuit that limits the output current to 36 mA. The output voltage starts being reduced when the output current reaches 25 mA and it is reduced to zero when the current reaches 36 mA. In the event of a short-circuit, the output voltage is cut and the overload warning LED lights up. The output power will only be re-established when the short-circuit is eliminated.

SECONDARY OUTPUTS

Model 122 M not only offers the added benefit of a fixed secondary output of 6.3 VAC but also includes a ±55 VDC adjustable output.

The 6.3 VAC secondary output may be used for the cathode heater circuit of Sigmatron’s ST-121 Cathode Ray Tube or for the light bulb commonly found on any Millikan apparatus.

The voltage of the ±55 VDC secondary output can be adjusted to any value between -55 VDC and +55 VDC. This output can be used to power Model ST-121 Cathode Ray Tube’s deflecting plates in order to demonstrate the effect of an electrostatic field on the beam’s trajectory.

Technical Specifications
Ref.	20-03217
Input Voltage	120 VAC ±10%
Power Consumption	50 W max
Input Protection	Slow Blow type 750 mA fuse, 250V (5x20mm)
Output Voltage	Output (1): 48 to 350 VDC, 25 mA max Output (2): 6.3 VAC, 2 A max Output (3): ± 55 VDC, 5 mA max
Regulation	Output (1): less than 1.0%
Filtration	Output (1): less than 0.5 % residual voltage of max voltage
Output Protection	Output (1): current limitation protection circuit (36 mA) Output (2): by means of input protection fuse Output (3): current limitation protection circuit (5 mA)
Indicator Lights	Power on, overload
Voltmeter	Three-digit digital meter for output (1)
Output Terminals	International color code compliant (positive pole is red, and negative is black)
Standards	CSA: electrical isolation between output terminals and input voltage
Color	Base: metallic gray - Cover: green
Dimensions	170 x 210 x 90 mm (L x W x H)
Weight	2.6 kg
Guarantee	3 years, parts and labor