Although the Programmable Power Resistor re-uses some components, many design ideas and a good portion of the software of the Programmable Decade Resistor (Programmable Precision Resistor), there were many changes and also some improvements regarding some aspects of the mechanical construction and the code. Rear panel with two 60mm fans, USB connector and Line input Features and specs So now it’s time to present the feature list/specs: ...
The Programmable Power Resistor consists of two large boards: The User Interface and Controller Board and the Relay and Interface Board. Because of the use of relays that isolate the input from the circuits, all circuits can be and therefore are earth-referenced. The only microcontroller, a STM32G441RBT6, is located on the User Interface and Controller Board. It implements a SCPI interface via USB (VCOM), the user interface and the logic to control the relays. All relays, the relay driver circuits, some external and internal interfaces and the AC/DC converter can be found on the **Relay and interface Board **. ...
The HP/Agilent 6632B is a remarkable power supply. There are some similarities with the mobile communication DC source 66309D I “repaired” recently: The 6632B is optimized for a fast transient response and it has a low current range too. But the circuit and its properties differ significantly. One important aspect: Where the 66309D only has a downprogrammer that doesn’t track the current setpoint, the 6632B goes all-in: It’s a two-quadrant power supply - able to source and sink current over the full operating range from 0-20V at 0-5A in CV and CC mode. ...
In the last post we had a look at a simple topology that allows us to switch between a series and a parallel connection of two resistors: Now we’ll nest these structures so that we have four resistors: The interesting part here is that two of the four switch states of the outer structure don’t provide any new resistance values: With S1aS_{1a} open and S1bS_{1b} bypassing the R1bR_{1b} we’re left with R1aR_{1a}. Again, this assumes the R1a=R1bR_{1a} = R_{1b}. If S1aS_{1a} is closed and S1bS_{1b} in the upper position, then the total resistance will be 0, exactly like with only R1aR_{1a}. Here I assume ideal switches. The series and parallel connection of both R1aR_{1a} and R1bR_{1b} alone is worth it though. ...
For the performance checks and calibration of my Agilent 6811B AC Power Source/Analyzer (375VA) I need a 20 Ohm resistor with a ton of power handling capability. The original plan was to mount 8 wire wound 50W resistors on a heat sink and be done with it. Then I thought: Why not reuse all the code I’ve already written for the programmable resistor and build a programmable high power resistor that can complement my DC load for AC applications. ...
A few days ago I got my hands on a faulty Agilent 66309D Mobile Communication DC Source. To be honest, I don’t think I need it, but it was pretty cheap and I was looking for something to either repair or potentially salvage the case of. The Mobile Communication DC Source is a specialized power supply. It not only has an improved transient response, but also a few other features not found on standard power supplies (e. g. E363x, E364x). The list for the Agilent 66309D includes (not necessarily exhaustive): ...
Currently, the unit’s setpoint accuracy isn’t all that great (readback resolution is limited as well, but shows the offset): Regardless of the range it has an offset of about +20 mA. Sure, for a unit capable of 60 A that seems reasonable, and well within its specs of ±0.1% ±75 mA. But since I’ll use it in the low range (6A) most of the time and likely often even well below 1A that doesn’t seem too great, does it? ...
I recently got my hands on a HP 6060B System DC Electronic Load (later also sold as Agilent 6060B). My unit has option 020 installed: Comically large binding posts also on the front panel. This option certainly is not unheard of, but not too common either. Retrofitting is possible, but can be quite some work. Huge binding post also on the front panel thanks to option 020 ...
I got my Agilent 6611B AC power source/analyzer a few weeks back, but hadn’t used it as much as I wanted. The reason was simple: The connections are made with rear mounted screw terminals - hence it was just a bit inconvenient to interface with products and circuits. The solution was really simple: A Hammond Manufactoring enclosure equipped with a European " Schuko"-style power outlet and some additional safety-banana jacks for prototyping. ...
For projects like the programmable resistor I was looking for a case, preferably made of aluminum and 19" compatible. In order to save some space on the desk I hoped to find one with a width of 42HP (i. e. half width). What I found was a beautiful case made by ELMA (2 RU, 42HP), called Stylebox 15 Standard. The only major disadvantages of the specific model I got were the low depth of 245mm and the fact that there are no ventilation slots at all. Fully assembled with the parts provided, that is… ELMA offers a huge variety of variants, so if your pockets are deep and you happen to have your own business, you can pick and choose and configure it the way your project needs it to be. If it’s just a hobby, you might not be as lucky… ...