I was on it yesterday and wanted to know what do you think about that.
On the Kristian Blasol youtube channel :
The email:
Hi Kristian,
my name is Lennard Kreuzer iam a Student from Germany.
Inspired by your Videos ive used your Powersupply idea and had some
problems with it. I supportet 1 row 84TE of Modules with it, ive used
4700uF + 3300uF at the input. It worked but i never testet the Voltage
under Load conditions only with a few Modules installed. With haevy
patching i noticed strange behavior the OSC where not stable anymore. So
i dissassembled everything and took it to the bench. I testet the suply
under Load and it produced 0.7A max with a voltage of 7V and with
horrible 1V Ripple.
so ive simulated it with LT-Spice and wanted to share my findings.
An 12V Transformer outputs about 17V Amplitude (12V*1,41). The Diodes
have about 1V of drop so 16V are coming in to the Caps. The Regulator
needs about 2V to work properly. So if the Input Volatage drops from the
16V under the 14V mark it cant hold the 12V. In my Simulation you can
see that even with more Capacitance at the input the maximum load that
it can support is about 40 Ohms. 12V/40 Ohm = 0.3A = 300mA. This will be
the maximum Current at 12V that this supply can provide with 12V ac
input before the Voltage drops. In my Simulation i used 0,1 Ohm
resistance in the Transformer itself and none for Cables. So it might be
less than 300mA.
My solution for this is easy: Use a 15V or even 18V Transformer.
15V*1,41=21V so after the drop 20V can charge the Caps and there are now
6V drop to the Critical 14V mark. As you can see at the Immages that i
should support up to 1A. probably a bit less do to resistance of
wires… The 12V Input Voltage simply can not Charge the Caps enough.
The Immage shows my Simulation. I Used 4700u + 3300u Caps and i am
Simulation only the +12V Rail. To simulate the bypasscaps at the Modules
i put a 1000uF Cap after the Regulator.
The Blue curve is the voltage at the Caps (before the Regulator), green
after the Regulator. Left side shows 12V ac with 0.5A Load and 1A Load.
The right side shows the same Loads but only with 15V ac input.
Your selfbuild Modules are by far not powerhungry i suggest. So your row
will maybe draw less than 300mA. But with Modules from the store, they
can have 100mA on +12V or higher for one Module. So with a 15V input the
Powersuply can support well over 0.5A witch is the avarage load per 84HP
Row at least in my system. I thinks i would be a good idea if you would
make a Video about this. Recomending a 15V Supply for all the DIYers out
there. So that 1 Supply can safly support at least 1 row.
Keep up the good work and Greetings from Germany
See here
). Transformers output more than the nominal voltage, until you’re approaching VA max ratings.