Wednesday, 28 October 2015

DIY Digital Oscilloscope Kit

So, I've been buying a load of equipment from Bang Good. It really is a great site, with a lot of electronic equipment at a great price.

My latest piece of equipment is my DIY Oscilloscope. As most hobbyists know, oscilloscopes can be expensive to purchase, but this little beauty comes in around $24. Like the DIY Adjustable Voltage Power Supply in my last blog post, it comes unassembled. Well except for the 48 pin Cortex M3 processor from ST Micro Electronics, which would be difficult for most hobbyists. All the other components are straightforward enough to attach and connect to the right place. There is less documentation with this device than there is in the DIY Power Supply. This is slightly annoying when trying to figure out what components go where. There's also a lot more components on the board, so it will take longer to build. 

The device itself comes with a 2.4" TFT screen. Unfortunately it's not a touch screen interface and the 4 buttons have to be used to navigate the settings on the screen, which is a little awkward to use. It also comes with a BNC connector cable with crocodile clips. There are also 3 switches to select between GND/AC/DC coupling, voltage divisions and amplitude magnification. It does not come with it's own power supply and the 9V input must be supplied externally. It also does not come with a case, which would have been nice. 

It is fun to build these devices, although not trivial, it's even better when they can be used as a tool to verify all of our other projects. It's not a full on professional Oscilloscope, but it does have quite a number of useful features. There's Automatic and Normal sampling as well as the single shot. It can capture on either rising or falling edges. We can change the trigger level as well and change time division from 500s down to 10us. I have to admit anything above 1s is a little excessive for capturing on a scope of this type.

You can see the working oscilloscope in the 2nd attached photo, powered by the previously mentioned DIY Voltage Adjustable Power Supply. 

If anyone else has ever bought this and had issues with it, comment below and let me know what you think or if there's anything else you would change about it. 

If you're looking to purchase this kit, check out the following link at Bang DIY Digital Oscilloscope Kit

Sunday, 25 October 2015

DIY LM317 Adjustable Voltage Power Supply Board Learning Kit With Case

I recently bought the LM317 Adjustable Voltage Power Supply Board from Bang For about $12, you can't go wrong. Bang Good is a Chinese distributor based in Guangzhou, China. The shipping was cheap enough as well, although you'll be waiting up 4-5 weeks to receive it. If you're not in a rush, then it really is a cost saving. 

The Power Supply comes with an adjustable signal generator output, that provides a pulsed signal. It also comes with an onboard buzzer and a number of LED's that indicate output voltage levels. The most useful part is the single piece voltmeter. It illuminates to tell you the output voltage, which is very useful to know before you attach it to anything else. 
All the components come not populated on the board and you have to be assembled yourself. So you'll need a soldering iron and some solder. I also recommend a decent flux pen as well; it ensures a decent connection and reduces dirt. The kit comes with a detailed diagram of where to place each component. I will admit you will also need a multimeter as some of the resistors are not labelled. Unless of course, you can read the colour band markings. 
Once built, it's a solid little power supply and I have used it for many DIY projects. The output voltage ranges from 1.25V to 12V and is continuously adjustable.
As you can see in the attached photos, we see the board as it arrives, after it's built and an updated photo too. In the updated version of the board, I used a 2A, 250VAC switch on the secondary side of the transformer to enable me to turn on and off the power supply when I want, without having to unplug the device all the time. I'm not sure if you can see it fully, but I've also replaced the standard 2 pin EU plug they supply with an old UK, BS1363 plug I had lying around. I had to insert a connector block for the live and main and I connected the earth to the underside of the transformer for safety purposes. I like to add extra protection if needed. I could connect the earth to the ground on the power supply board in order to remove my floating output on the power supply, but this proves problematic with various projects. It also a potential cause of electric shock based on whatever projects I connect it to. For example, when connecting it to systems that use the floating reference to increase the voltage. By connecting the ground to Earth, I would remove the possibility of doing this.

All in all, this is a very useful product. It's small and to the point. I really like the clear perspex box they supply with it and I'm also a fan of how it screws together using T-shape cutouts. There's little else that I would add except for what I've already mentioned. Well maybe I'd increase the height of the potentiometer for adjusting the signal generator output, which is a pain to try and get at. You'll need a smaller than 4.5mm Phillips head screwdriver to get at it.

If anyone else has ever bought this and had issues with it, comment below and let me know what you think or if there's anything else you would change about it. 

If you're looking to purchase this kit, check out the following link at Bang DIY LM317 Adjustable Votlage Power Supply