Hi Gents,
I received the delivery of PCBs last week and have been busy soldering up a couple of boards to test that everything works.
I am happy to say that this PSU works as intended and has even exceeded my expectations!
Here is a pic of the board mounted to a fairly sizable heatsink on the test-bench. You will notice the two green bridges on the front left corner: When the board is used for currents less than or equal to around 2 Amps continuous, then we would have a pair of resistors mounted there. Over 2 Amps continuous and the resistors tend to get too hot, therefore for higher currents the resistors are replaced with the wire bridges:
...and the same board connected to a toroid. The toroid in question is a Nuvotem Talema 300VA with dual 25V secondary windings. For the test I only had one of the pairs of secondaries connected:
With the transformer being 25V AC output, that will rectify to around 35.35V DC. My no load voltage (after the capacitor bank) measured in at 34.6V DC. This drops down to around 27.5V DC under a 4 Amp load, so for my bench test I decided to set the output voltage to 25V DC which would provide some headroom for the regulation circuitry to do its work.
The output voltage is set using a 25 turn trimpot on the PCB near the output terminal:
Naturally, the first thing I tested was that everything works when switched on, no magic smoke escapes, and we are actually seeing some output voltage. That out of the way, the next bit was to test how well the regulation works. For this I decided to get a benchmark measurement first.
On my bench I have a Keithley (Tektronix) 2231A triple output precision power supply which I decided to run through its paces as my reference:
The regulation test is very simple: Set the output to 25V DC, and use my electronic load to draw a constant 1 Amp current out of the supply. My multimeter (Agilent / Keysight 34461A) is then connected to the wires coming into the electronic load and from there I measure the DC Voltage and track this over time to give me an indication of how well the PSU regulates the voltage.
After allowing the PSU to warm up for about 15 minutes, I started the test. The test itself was run for around 5 minutes. This is the result obtained from the Keithley (the display is only showing the graph for the last 60 seconds):
The picture quality is a bit dodgy, but in a nutshell here are the results:
Minimum Voltage: 24.9877
Maximum Voltage: 24.9898
Average Voltage: 24.98928
Standard Deviation: 0.00046
Measured over 1007 samples
So, the difference between the minimum and maximum is 0.0021 Volt
Divided by the average voltage of 24.98928 that gives an absolute regulation figure of around 0.0084%
Pretty impressive figure that, and a worthy benchmark! Also very impressive is the standard deviation which is only 0.00046 :sweat:
Next up is the humble little black PALADIN circuit board, nervously sweating away in the shadowy corner - intimidated by the impressive results achieved by the Keithley...
The adjudicator steps up, checks the connections, and allows the regulatory 15 minutes warm-up time. The allocated warm-up time is over far too quickly as the bell rings and the test of manhood begins...
The 5 minute bell rings to signal the end of the test and the PALADIN has barely worked up a sweat! The results are in:
Minimum Voltage: 25.0342
Maximum Voltage: 25.0350
Average Voltage: 25.03457
Standard Deviation: 0.00018
Measured over 1101 samples
So, the difference between the minimum and maximum is 0.0008 Volt
Divided by the average voltage of 25.03457 that gives an absolute regulation figure of around 0.0032%
And we have a winner! The humble PALADIN Voltage standard takes the lead with an impressive regulation accuracy of 0.0032% vs the Keithley's result of 0.0084%!!! A 262.5% improvement on the Keithley precision bench supply :clap: :dance: :dance: :dance:
So folks, it seems the PALADIN Voltage Standard (Light Current) boxes significantly above its weight and price class even when compared to big brand precision bench-equipment ;D
I have some pretty serious measurement equipment here, but am unable to measure ripple and noise on the line with the equipment I have - it is below the noise-floor of my measurement equipment which is to say that it is impressively tiny.
The only thing remaining then is to hook a pair of these supplies up to the new PALADIN Buffered Linestage preamplifier boards (still to be soldered up) and have a listen!
Feel free to post your comments or questions - I am happy as always to discuss and explain!
Kind Regards,
Ian.
PS: I am finalizing the pricing from the BOM for these - will post as soon as I have everything figured out. In the meantime, feel free to let me know if you would like to put your name on the pre-order list.
I received the delivery of PCBs last week and have been busy soldering up a couple of boards to test that everything works.
I am happy to say that this PSU works as intended and has even exceeded my expectations!
Here is a pic of the board mounted to a fairly sizable heatsink on the test-bench. You will notice the two green bridges on the front left corner: When the board is used for currents less than or equal to around 2 Amps continuous, then we would have a pair of resistors mounted there. Over 2 Amps continuous and the resistors tend to get too hot, therefore for higher currents the resistors are replaced with the wire bridges:
...and the same board connected to a toroid. The toroid in question is a Nuvotem Talema 300VA with dual 25V secondary windings. For the test I only had one of the pairs of secondaries connected:
With the transformer being 25V AC output, that will rectify to around 35.35V DC. My no load voltage (after the capacitor bank) measured in at 34.6V DC. This drops down to around 27.5V DC under a 4 Amp load, so for my bench test I decided to set the output voltage to 25V DC which would provide some headroom for the regulation circuitry to do its work.
The output voltage is set using a 25 turn trimpot on the PCB near the output terminal:
Naturally, the first thing I tested was that everything works when switched on, no magic smoke escapes, and we are actually seeing some output voltage. That out of the way, the next bit was to test how well the regulation works. For this I decided to get a benchmark measurement first.
On my bench I have a Keithley (Tektronix) 2231A triple output precision power supply which I decided to run through its paces as my reference:
The regulation test is very simple: Set the output to 25V DC, and use my electronic load to draw a constant 1 Amp current out of the supply. My multimeter (Agilent / Keysight 34461A) is then connected to the wires coming into the electronic load and from there I measure the DC Voltage and track this over time to give me an indication of how well the PSU regulates the voltage.
After allowing the PSU to warm up for about 15 minutes, I started the test. The test itself was run for around 5 minutes. This is the result obtained from the Keithley (the display is only showing the graph for the last 60 seconds):
The picture quality is a bit dodgy, but in a nutshell here are the results:
Minimum Voltage: 24.9877
Maximum Voltage: 24.9898
Average Voltage: 24.98928
Standard Deviation: 0.00046
Measured over 1007 samples
So, the difference between the minimum and maximum is 0.0021 Volt
Divided by the average voltage of 24.98928 that gives an absolute regulation figure of around 0.0084%
Pretty impressive figure that, and a worthy benchmark! Also very impressive is the standard deviation which is only 0.00046 :sweat:
Next up is the humble little black PALADIN circuit board, nervously sweating away in the shadowy corner - intimidated by the impressive results achieved by the Keithley...
The adjudicator steps up, checks the connections, and allows the regulatory 15 minutes warm-up time. The allocated warm-up time is over far too quickly as the bell rings and the test of manhood begins...
The 5 minute bell rings to signal the end of the test and the PALADIN has barely worked up a sweat! The results are in:
Minimum Voltage: 25.0342
Maximum Voltage: 25.0350
Average Voltage: 25.03457
Standard Deviation: 0.00018
Measured over 1101 samples
So, the difference between the minimum and maximum is 0.0008 Volt
Divided by the average voltage of 25.03457 that gives an absolute regulation figure of around 0.0032%
And we have a winner! The humble PALADIN Voltage standard takes the lead with an impressive regulation accuracy of 0.0032% vs the Keithley's result of 0.0084%!!! A 262.5% improvement on the Keithley precision bench supply :clap: :dance: :dance: :dance:
So folks, it seems the PALADIN Voltage Standard (Light Current) boxes significantly above its weight and price class even when compared to big brand precision bench-equipment ;D
I have some pretty serious measurement equipment here, but am unable to measure ripple and noise on the line with the equipment I have - it is below the noise-floor of my measurement equipment which is to say that it is impressively tiny.
The only thing remaining then is to hook a pair of these supplies up to the new PALADIN Buffered Linestage preamplifier boards (still to be soldered up) and have a listen!
Feel free to post your comments or questions - I am happy as always to discuss and explain!
Kind Regards,
Ian.
PS: I am finalizing the pricing from the BOM for these - will post as soon as I have everything figured out. In the meantime, feel free to let me know if you would like to put your name on the pre-order list.
