HISTORY:
I have been sorting and clearing out some boxes of old radio related equipment and came across this linear power supply.
I am hoping that may be useful on someone's workshop bench instead of living inside a dark, lonely box ...
This power supply was previously part of a Philips receiving system with an associated low power RF data transmitter.
Compact PSU with adjustable output voltages (internal adjustment) and a form of current limiting on one output.
PHILIPS - DC Power Supply
Country of origin is not indicated but the system unit this was used with was assembled here in Australia (many years ago!)
Technology: Linear
Model: V/910010/ENG 612 (I believe these were all Philips internal engineering drawing references)
Input: 240V AC 50Hz
Standard Australian AC 3 pin plug
Outputs: +13.6V DC @ 2.5A & +13.6V DC @ 250mA
Both outputs are not terminated, one has shorter leads than the other - this helps identify the type of output, please read below to understand this further ...
Both outputs are regulated
Circuit configuration is a pretty standard 723 voltage regulator and a TIP3055 power transistor.
Voltage output is adjustable - remove the top of the case, trimpot adjustment
One output is pretty "ordinary", 13.6V (adjustable) at up to around 2.5A rating and protected by an internal fuse. The fuse fitted is 5A
The other output is also 13.6V (again, adjustable) but just a little different in that a festoon lamp is used to limit the current flow. When the current exceeds 250mA, the voltage rapidly drops off and you get a nice little glow inside the case! This is a trick also used by Wharfedale in their vintage pro loudspeaker systems.
DIMENSIONS:
170mm depth x 95mm wide x 70mm height
WEIGHT: 2.2Kg
COSMETIC CONDITION:
USED
CLEAN
NO damage at all to the case
AC lead is undamaged, plug is good
TESTING:
A couple of notes about construction of this power supply ...
The case is Steel, two U shaped sections that fit one into the other and secured by 4x screws in the base.
There are NO feet but instead the base has 3 threaded holes for bolts - originally this PSU was designed to be side mounted onto some equipment.
There is NO ON-OFF switch, plug it in and it is ON
There is NO power ON indicator although the transformer lamination's do hum a little (not loud but you can tell the PSU is ON)
The fusing/current protection devices are all on the secondary of the transformer, the primary windings are directly wired to the AC power lead.
It may be that the new owner might wish to fit a small toggle switch and neon panel indicator (with a limiting resistor) and perhaps even a panel mounted fuse holder for the primary of the transformer .... there is plenty of internal space for these component additions.
Checked the DC outputs (load and no load conditions), there are two DC outputs and each is slightly different.
OUTPUT 1 (short leads): Voltage is adjustable, currently set at 13.59V
This is FUSE ONLY protected and the fuse is mounted internally but easy to reach once the case is removed. The fuse currently installed is 5 Amp (normal blo)
OUTPUT 2 (Longer leads): Voltage is adjustable and currently also set at 13.59V
Current limiting is achieved by the use of a festoon lamp inside the unit. As the current flow increases, the lamp filament limits the current. It starts to come into effect at 250mA flow and if for example 1 Amp is drawn from this output, the voltage is now only 3.8V AND you have a clearly visible lamp glowing inside the case!
I measured the ripple current with a 2 Amp load on Output 1 and a 250mA load on Output 2, measured AC ripple as less than 1mV
This power supply may be useful where you need a voltage just slightly higher than a standard 12V supply e.g mobile comms equipment but keep in mind that the current capabilities are quite low - fine for low power transmitters but no good at all for medium/high power transmitters. Most receivers or scanners designed for mobile use (13.6V DC input) will be fine with this supply.
After the testing, photographs etc I have now placed this power supply within a sealed clear plastic package to maintain the condition.
