<<<<   Index

Energy losses in aerial amplifier

If you have more TV aerial connections in your house, it may be necessary to use an aerial amplifier.
With 2 TV connections, the use of a (passive) splitter is sufficient in most cases, and reception on both TV's will be good enough.

With more then 2 TV connections, or when using long aerial cables, an aerial amplifier directly at the incoming signal socket is useful to prevent an interfering or snowy TV picture.
I use an aerial amplifier of brand: Hirschmann, the model number is: GHV30.
The energy consumption of this amplifier was 4.5 Watt, and it's on for 24 hour per day.

To reduce the power consumption of the amplifier, I build a new power supply in it.

The inside of the aerial amplifier.
With the original transformer.

The original power supply of the amplifier was build with the following circuit:

The transformer was an E-I core transformer of 15V 3.9VA.
The rectifier was a rectifier bridge with 4 silicon diodes.
The stabilizer was of type 7812, which requires at least 15V at it's input to do his work.
The current consumption (DC) of the amplifier is about 140 mA, this is the current from stabilizer to amplifier.
Across the elco's there is about 18 V DC, so across the stabilizer we lose 6 Volt.
So, the energy loss in the stabilizer is already 6V x 0.14A = 0.84 Watt.

I have replaced the power supply of the aerial amplifier by the following circuit:

The transformer is a toroidal transformer of 2x 9V 5 VA (toroidal transformers have less energy losses then E-I core transformers).
The rectifier consists of 2 schottky diodes, type MBR360 (gives less losses then 4 silicon diodes).
The stabilizer is of type LF120, which requires at least 12,2 V at it's input, for a stabilized 12 Volt output.
The output voltage of the transformer is reduced from 15 to 9 Volt, we now have about 12.63 Volt DC at the input of the stabilizer.
The value of the elco is increased from 1000 to 3000 μF, through this the ripple voltage across the elco's reduces from 1 Volt p-p to about 0.33 Volt p-p.
The minimum voltage across the elco (in the lower part of the ripple) is about 12.5 Volt, and this is enough for the stabilizer to do his job.

The toroidal transformer connected to the amplifier.
The two diodes are inserted into the transformer leads.


Here you can see the two extra elco's of 1000 μF, which are added.
The stabilizer LF120 is situated behind the elco's and screwed onto the housing.


The transformer fits nicely into the housing.
After closing the cover, the amplifier is ready.

After the rebuild, the power consumption of the aerial amplifier is: 2.3 Watt.
First this was 4.5 Watt, so the power consumption is almost reduced by halve, and the amplifier still works as good as first.
The saving is 4.5 - 2.3 = 2.2 Watt.
Per year this is a saving of 19.3 kWh.

<<<<   Index