Linear Power Supply Unit L-100

 264.00 288.00 Incl. VAT
 220.00 240.00 Excl. VAT

Low-Noise Linear Power Supply Unit (LPSU) for powering various analog/digital devices


In a world loaded with tons of Switched Mode Power Supplies (SMPS) it became clearer than never that even though its bulky size and weight, the Linear Power Supplies have more advantages than faults.

That’s why here is offered a small-size Linear Power Supply Unit (LPSU) suitable for replacing the noisy SMPSes used for powering a small PCs like Intel NUC, Lenovo ThinkCentres and many other, various digital devices like (small) amplifiers, DACs, audio players, Raspberry Pi-based boards, USB-powered digital equipment etc.


– Input voltage: AC 115V or AC230V (according to the destination country or user request)
– Output voltage: DC 5V/12V/19V/24V (user-defined values are also available upon request)
– Max. output current – 4.5A
– User selectable option for 8mm. aluminum front panel (black anodized)
– User selectable option for common mode AC filter on the input of the AC supply voltage
– Dimensions: 220x220x75 mm.
– Transformer Power: 100VA
– Weight: about 4.5kg
– Output DC cable with barrel jack 5.5/2/5 mm. (OD/ID)
– Possibility for different output connectors upon customer’s request
– Built-in trigger-type over-current protection (in case of protection’s engagement the unit must be turned off for a while in order to recover its normal work)
– Built-in trigger-type overheating protection preventing the unit from burning in case of serious malfunction
– Front panel LED
– Possibility for upgrade of DC cable with custom-made one

Schematic description

The regulator has all-discrete topology. No Operational Amplifiers are used. This allows complete design control over all operating points and parameters for superior performance. Low noise, high PSRR.
There is a bridge rectifier block on the input which is filtered with a massive electrolytic capacitor on the output. This greatly reduce the ripple charge voltage and hence helps for better output filtering.
The error tracking stage is based on a differential amplifier built with dual transistors chip which ensures the excellent thermal stability and equality of its parameters.
The differential amplifier is cascoded which greatly reduce the input noise influence over the error (differential) amplifier and Erly effect.
A Zener diode is used as a voltage reference. It is fed by a Constant Current Source attached to the output of the regulator which dramatically minimise the noise and ripple through the Zener (and hence at the input of error amplifier). The High-frequency Zener noise is additionally filtered by a Low-pass filter between Zener diode and error amplifier.
The output stage consists of two power-Darlington bipolar transistors working in Common-Emitter mode. This allows the regulator to work as a LDO (Low-DropOut) with smaller difference between Input and output voltages which diminishes the thermal dissipation over the regulation transistors.
At the input of the regulation transistors is placed trigger-type over-current protection network which engages at a given output current and turns-off them. Once the protection is engaged, it can stay in this mode for an unlimited period of time which prevents the system from doing any harm even in a human absence. In order to return to normal operational mode the regulator must be turned OFF for a while (to discharge the electrolytic capacitors) and then turned ON again.
And since SAFETY is a thing we care about a lot, a thermal switch is added in parallel with the over-current protection. This way even if the current protection is not engaged (which is almost impossible) the output regulation transistors will be turned OFF when their heatsink’s temperature reach 85°C.


Measurements of DC and AC voltages were taken with Keithley 2015 Multimeter while the spectrum plots were drawn using RTX 6001 Audio Analyzer. The obtained results are as follows:

– Line regulation (AC input voltage between 216 – 235 V): 0.05%
– Load regulation (DC output current between 0 – 4.5 A): 0.06%
– Output AC ripple voltage when loaded with real load (Lenovo ThinkStation M92p): 4.2 mV RMS
– Measured Power Supply Rejection Ratio (PSRR): -120 dBV for fundamental harmonic (100 Hz)

A DC cable ended with barrel jack 5.5/2.5 mm (OD/ID) is provided along with the unit. In case some different connector is required contact us prior to place the order.

Instead of the standard DC cable a custom made one can be used: https://www.atlhifi.com/shop/audio-cables/dc-cable-upgrade-for-l-100-lpsu/

This is a “star-quad” cable which consists of 4-wire AWG22 silver plated wires with PTFE insulation.

The unit is available with 8mm. aluminium front panel (milled and anodized) or without panel while retaining all functionality.

User can also choose between 4 fixed output voltages – 5, 12, 19 or 24V or Custom defined voltage.

In case you want a LPSU with Custom output voltage (different from the 4 listed above), please contact me via the contact form in order to discuss the possibility for LPSU production. Then in the process of ordering you should leave a note for desired output voltage.

Какво получава купувачът:
Пакетът ще съдържа 1 pcs. FULLY ASSEMBLED and tested Linear Power Supply in a steel case and 1 pcs. DC cable.

Забележка: The AC Power cable is not provided.

Устройството се тракспортира в рамките на страната със СПИДИ, плащане с наложен платеж и опция за преглед преди плащането.

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Low-Noise Linear Power Supply Unit (LPSU) for powering various analog/digital devices
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Допълнителна информация

Тегло 4.5 кг
Front Panel

Present, Not Present

Output Voltage

5V, 12V, 19V, 24V, Custom voltage

Синфазен филтър

Present, Not Present