Hi,
Yes, there is a new version of the schematic, but i want to talk about some other stuf...
This is a picture of the box where the LM723 power supply will be built in.
I decided not to use the smaller heatsink and to choose a larger model.
This heatsink comes from a DELL computer, this brand used very nice cooling material, which I have already used for several projects.
The CD box is to better estimate the dimensions, it is a CD from New Order and Joy Division are English bands and one of my favorites.
Front view.
This will probably be the setup of the transformer, 10.000uF C5 fan and the heat sink.
Also note the bridge rectifier on the side of the heat sink, now still glued at the moment of the photo, but it will be screwed on later.
This is one of the fans I have in stock which I have tested for this power supply.
It has been tested up to 18V power supply voltage and I will offer it up to 15V.
Most fans have a fairly large voltage range, just look at the big brands in the datasheets.
But apply what you like yourself, this is a fan of not so high power that cools much better at 15V, this with little noise.
Of course, the fan wears faster when running at 15V for a long time, but this will not happen too often, only at low output voltages and at the maximum current this power supply can deliver.
It is not a production power supply, it is a power supply for my LAB Bench, for testing various circuits.
But tlater I tell you more about the fan and its control.
Here you see the bottom of the heatsink that is normally printed on the Intel processor.
First I mounted four nylon bushes to isolate the heat sink.
The Collector of the 2SA1943 is mounted directly on the heat sink for the lowest thermal resistance.
This helps with the efficiency of the cooling block and also helps to keep the chip temperature of the 2SA1943 as low as possible and eventually results in a lower fan speed and noise.
All parts that are screwed onto the cooling element are provided with a thin layer of silver compount just like a processor cooling.
This picture shows what I want to mount on the cooling block, that are many parts.
The white part is "clickson" of 50 Celsius which interrupts the 230V mains voltage when you exceed this temperature.
I have here the 50 and 60 degrees Celsius in stock.
There will be two of these "clicksons" in this power supply, I will also mount one on the transformer.
These are the parts that are most important and for that I drilled holes and tapped M3 thread.
The setup was chosen with care and in the end it took me two hours to come to this setup.
I wanted the wiring to be as short as possible and the two big heat sources, that is the 2SA1943 and the 4.7 Ohm resistor not too close to each other and not too close to the edge of the heat sink.
With this setup that I show here, I think I succeeded well.
Right next to R34 the 0.22 Ohm resistor, we assemble the driver transistor for the 2SA1943.
There is still room left for the MOSFet that will control the fan and another power resistor that will only dissipate 1-Wat maximum.
When I have determined the position of all the parts on the cooling element, I'll flatten the heat sink and also the 2SA1943 transistor for the best heat transfer.
This is the fan controller, I have used this schematic several times with good results.
I designed it so that the fan always runs at a minimum speed at which the fan runs reliably.
The noise level at this speed is so low that it can only be heard close to the fan.
I also chose the fan on Power On which runs at full speed for a short time.
I use a MOSFet to control the fan, the sensor is a small glass of NTC that is mounted in the Heatsink just below the chip of the 2SA1943.
R5 in the schematic sets the minimum fan speed.
If the NTC measures above a certain temperature, the IRF540 slowly starts to conduct.
P2 sets the temperature at which the fan starts running at a higher speed.
Usually I set it in such a way, that around 35C heatsink temperature the speed increases.
Always running the fan ensures, among other things, that the temperature inside the housing and provides more DC stability.
Depending on the fan used and how well the NTC is connected to the heat source, the IRF540 can be replaced by an IRF840 for a low power fan.
The IRF840 is less Transconductance about 5S and the IRF540 is 9S.
This is the starting point for the 230V grid voltage side.
Here too I have to do some tests to determine the optimal component values.
This is it for today.
Kind regards,
Bram