Description

Loading

The Lambda LL-902-OV Regulated Bench Top Power Supply 20V / 0.65A

This power supply is in working and functions as intended. It is missing a binding post and two cosmetic discs for knobs.

Lambda Model LL-902 bench-type IC regulated laboratory power supply which provides an adjustable d.c. voltage range of 0-20 volts at currents from 0 to 0.65 ampere.

All-silicon DC power supply using integrated circuit to provide regulation system except for input and output capacitors, rectifiers, and series regulation transistors.

Convection cooled
Multi-position operation: Lies flat or stands erect.
Die-cast aluminum construction weight: less than 6 lbs.
No overshoot: on turn-on, turn-off or power failure.
Adjustable current limiting: 0 to 110 % of rating.
Controls: Course voltage adjust, fine voltage adjust, current adjust, ON/OFF switch, meter function switch.

Built-in tracking over-voltage protection

Regulated voltage:
regulation, line …….. 0.01 % + 1 mV.
regulation, load ……. 4 mV.
ripple and noise ……. 250 uV RMS 1 mV pk-pk .

DC output voltage ranges: 0-20V.

Temperature coefficient: (0.015% + 300 uV) 1°C 105-132 VAC 47-440 Hz (current ratings based on 57-63 Hz).

Derate current: 10% for 50 Hz operation, 182-242 VAC 45-440 Hz.

Overload Protection
Electrical: External overload protection: automatic electronic current-Iimiting circuit limits the output current to a
preset value, thereby providing protection for load as well as the power supply.

Automatic current limiting: Adjustable from 0-110% of rating.
Overvoltage protection: Built in tracking over-voltage protection.
Input connections: Heavy-duty, 3-wire line cord.

Output connections: 5-way binding posts on side panel.
Meter: Dual function meter measures voltage or current output as selected by meter function switch on front panel.
Controls: DC output controls; course voltage adjust, fine voltage adjust and current adjust on front panel.
Adjustment of voltage control allows over-voltage protector to track voltage output automatically.

Power
on-off switch on front panel.
Meter: function switch to measure output voltage or current.

Physical data
Size: 5 5/8″W x 5 1/2″H X 3 7/8″
Weight: 6 Ibs.

The Ferroresonant Transformer

The ferroresonant transformer is an effective means of compensating for poor line regulation. The capacitor-input filter supply can be transformed into an improved regulated supply by replacing the linear input transformer with a ferroresonant transformer which provides regulated a.c. to the rectifier-filter section and improves ripple attenuation by squaring the sine wave. Line regulation and ripple waveform change are caused by the resonance set up between a transformer winding and an external a.c. capacitor.

The ferroresonant transformer, inherently a current-limiting device, provides automatic protection against overload. Because its major drawback is sensitivity to line frequency changes, it is used only where line-frequency stability is assured. A typical ferroresonant power-supply specification includes: line regulation of 2% for line changes from 105 to 132 volts a.c. or 132 volts a.c. to 105 volts a.c. for any load between 25% and 100% of full load; load regulation of 5% from 1/2 load to full load; frequency regulation of 2.4% for each cycle change in line frequency; and ripple of 1% r.m.s.

The simple ferroresonant power supply is the most reliable regulated power supply in use today. Prerequisites for its use are: fixed input frequency, small load variations, and a tolerance for slow response to transients. A ferroresonant supply requires many cycles of input frequency to recover from any line transient.

Feedback-Controlled Regulation

The demand for better regulation imposed by today’s sophisticated circuits and complex electronics systems is best met by the feedback-controlled power supply. This type of regulated power supply is capable of maintaining a substantially constant output voltage at a selected value, even though changes occur in the a.c. input voltage (within specified limits) and /or in the rated d.c. load current. In addition, these power sources can be made short-circuit-proof, preventing damage to the supply caused by load fault and can be made load-protecting by using over-voltage protectors to prevent load damage caused by internal supply failure.