If you are looking for an inexpensive kit build project that comes together nicely and works well to boot check out the DSO Shell 15001K Oscilloscope Kit.
At $22.00 including shipping from China this is a no brainer. With a 200K bandwidth (Perhaps a bit of an exaggeration) it is undersized for many applications but still is a good tool for Audio and lower frequency servicing as well as a good educational tool for the experimenter or enthusiast. This model of the unit comes with all the SMD components installed. The through the hole components, switches and connectors are left for the kit builder. Here is what comes in the package:
Note that while you see a probe in some of my pictures this is not included in the kit, nor is the 9 volt power supply. I found that the small wall warts that I use for the Arduinos worked well. I also put a battery pack on the back of one unit so that I have a portable model. The manufacturer cautions that 10 volts is the high limit of the power supply and damage may result if the unit is powered with a higher voltage.
Here are what the circuit boards look like out of the box:
The kit comes with 4 pages of assembly instructions, calibration, and operation manual. While it is over all adequate it takes a lot of looking close and a thorough reading to get it right the first time. I have build three so far and I still can't quite get it right. It is not that the correct procedures aren't explained or illustrated somewhere on the pages it is just that it is not a totally smooth sail and I have a tendency to use my intuition too much. Fortunately a couple redos are permitted. The solder points are very small and a little challenging so this may not be a kit for a first time builder. Better to have some soldering experience first though it is doable if someone with experience is supervising a beginner.
The resistors supplied are very small and 5 banded. My 68 year old eyes had a challenge with them so I just metered them and put them where they belonged. If you happen to have some of my special tungsten carbide meter probe tips you can check 1/8 watt resistors one handed like this:
When the main board is fully populated they have you plug it in to check for proper operation. The instructions are a little out of sequence so it is necessary to populate the board and then go back to the first instruction on the list telling you to test it. At this point all one can do it see the screen and toggle the function buttons.
I found that the vias did not pull the solder in quite as easily as I would have liked so a good inspection of both sides of the board after soldering allowed me to dress up a couple questionable looking joints. The Analog board is the board where the bulk of the through the hole components must be installed. Over all the instructions were good and the components easy to identify. On the first two units that I built I mounted the adjust control backwards on its board. This does not harm anything but the unit will not work properly. If the instructions are read carefully they have a small box with a red print warning not to do it the way I did. Once this error was corrected both of the first two units worked properly. Here is the small board showing the side not to mount the control on.
The analog board comes with two sets of header pins so that during calibration the main board can be off set to allow access to the adjustments. While in this position one can check voltages and tune the input to display a clean square wave.
One feature that I was really pleased with is the ability to toggle on and off a list of measurements. Usually on a meter this size and cost one is left to guess what the digital data is. Here is what the unit looks like with the measurements displayed:
I put a battery pack on the back of one unit to make it more portable and purchased a set of $10.00 Oscilloscope probes for the units. The probes like the oscilloscopes came with free shipping but this time the Chinese had them shipped to me from the Seychelles. The ways of the electronics world are hard to believe. I am enjoying this era of free trade and exchange of products. I wonder how long before the politicians see what is going on and screw everything up. Any how if you like to build things this was a fun little project with very little financial risk involved. Here is a picture of the back of my unit with the battery pack and a picture of a completed unit.