| IDHT
Heater supply
This module is intended to supply the heaters of indirectly
heated tubes. Their supply isn't half as critical as
the supply of directly heated tubes. Its' main use is
feeding phono and linestage tubes, to keep the hum levels
down.
Why this module? It is compact, very low drop, does
the full job from AC in to DC out over a range from
2.5V to 10V. It is able to supply a stable 1A -6.3Vdc
voltage from a 6.3Vac winding !
Technology
The heater supply uses Schottky barrier diodes for rectification.
They provide clean switching and inhibit low voltage
drop. 2 filter capacitors (4.700uF each) smooth the
voltage. A discrete design, low drop voltage regulator
feeds a power transistor at the output.
A
10-turn trimmer allows for accurate adjustment of the
output voltage.
Application
More tubes can be connected in parallel, assumed their
respective heaters are at equal potential. If heater
potentials are different, separate modules (and transformer
windings for each module) are required. The heater reference
needs to be connected close to the tube The total output
current is limited to 1.5Adc, mainly due to heat dissipation.
The
module can also be applied to feed other circuits
A fine example of a Squeezebox power supply is shown
here
(pdf-file, Dutch only)
Specifications
• Output adjustable between 2.5V and 10V (modules
are of factory adjusted to 6,3V)
• Output current maximum 1.5A
• Input voltage should not exceed 1 V above specification
(see application info - to be written)
• Minimum input voltage 4 Vac
• Output noise < tbd uVrms (10Hz - 20kHz)
• Output hum < tbd uVpeak at 100Hz / 120Hz
• Output impedance < tbd mOhm
• The heatsink is not electrically
isolated from the circuit and should be isolated from
the chassis
• The output is not short circuit
proof
Mechanical
• Total size 40*60*40mm (W*L*H, heatsink included,
standoffs excluded).
• Weight each 60 gram (excluding packaging)
• Hole pitch 31* 51mm.
• Needs 8mm stand-offs to mount on chassis, supplied
with modules.
Warrantee
5 years of warrantee are valid for the heater supplies,
assumed they are built in according application information.
Safety
Though this is a product which if handled properly is
save, it is surrounded by high voltages. Working with
high voltages requires safety measures and professional
behavior. Tentlabs takes NO responsibility for accidents
resulting from improper usage or handling.
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