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