Welcome to a new voltlog, today we are building a very simple constant current regulator based on the LM338 linear regulator. This is a very robust and stable classical regulator that is being manufactured by many big names like ST and TI, it has quite a high output current rating of 5A continuous, it even comes in a TO-3 can package but today we’re going to use a TO220 which is more commonly available.
To make a constant current regulator out of this, is very simple, the datasheet gives us the circuit we need to use and we only need a low value resistor to do that plus the optional input bypassing cap which is 0.1uF. We’re going to use this formula to calculate the value of the resistor, so the output current is equal to the Vref divided by the value of the resistor.
So I discovered this module a few months ago and it’s been sitting in a box since then, I almost forgot about it, until a few days ago when I decided it will be a good idea to do a video on the subject.
Let me give you a few details on the specs of this module and as usual it’s pretty difficult to find the information as it’s the case with every new module coming out of China. First of all we have an input range of 0-60V and 0-10A and a 5V rail is needed to power the module itself. It has a voltage measuring accuracy of ±0.2% + 0.2% full scale which sounds strange because these figures are usually given in a percentage plus or minus a number of least significant digits. The current measuring accuracy is ±0.4% + 0.3% full scale.
The meter is basically capable of measuring with a resolution of 1mv and 1mA (however the accuracy is quite bad, as shown in the video) which is quite nice and useful (not really useful with bad accuracy) for projects like DIY power supplies or DIY electronic loads. It can also display the power in watts with a resolution of 1mW as well as showing the load impedance.
Welcome to a new voltlog, today we are going to answer the question how fast can you update an e-paper display, is it suitable to display live updating values from a sensor for example? Some people asked these questions in the comments of previous videos so I am doing some tests to try and answer these questions.
Now there will be a big difference between trying to update the whole screen and trying to update just a small section. And that delay might also be related to how fast the processor can send the information to the display. So for example measuring the time passed between sending the first byte of data to the display and the last byte going out is not that relevant, it might just be a slow processor, and the display could accept data much faster.
Also in the case of an Arduino the ram size is very limited so a full buffer could not be implemented. This means sending of the data to the display is done inefficiently increasing the time it takes for a full update.
This is just a short follow-up on the e-paper display video. It was brought to my attention by one of the viewers that banggood is shipping the bare display instead of the module as whole display + pcb + cable.
Welcome to a new voltlog, in a previous video I showed these C5W LED bulbs that I got from ebay they were very cheap so I put them to a test and discovered they reached very high temperature in just 15 mins of running in free air which got me concerned, the fixture of this bulb could melt.
So I guess a gadget like this is worth 10$ because you could replace that linear breadboard power supply with a more efficient one, which will give you voltage and current display as well as adjustable output.
Here are some images I took during the teardown of the mini power supply: