We all agree that hobbyist or engineer should have proper bench oscilloscope for everyday use. They have all standard features including built in screen, interchangeable probes and convenient knob controls. Anyway if you are looking for temporary cheap solution, you can try building your own oscilloscope. Luckily you don’t have to make it from scratch because there are many projects and kits available that are cheap but powerful enough to fit most of basic needs.
Some people have passion on building old gear simulators on modern hardware. Some of you may remember old BASIC machines that run on 8080 processors. If you look at hardware specs – they were really scarce: 1k of user RAM, 1k of display RAM, 8k for BASIC ROM and 2k of monitor ROM. Simply speaking almost any modern microcontroller can house such parameters inside memory and have more than enough of processing power. jscrane have built an emulator for this machine on Stellaris Launchpad.
Launchpad has 16k of RAM which was divided in two parts – 12k for main memory and 2k for the display. It has plenty of flash (256k) where all ROMs can be placed. Simulator supports 30 lines of 40 characters on a display, which is a bit less from original (32×48) but this limitation seems to be on a 240×320 display. There is also an SD drive attached, and PS/2 keyboard. Programs can be loaded from SD card really fast as the programs are limited to 14k. For more info and source files refer to GitHub.
VFD or other tube based indicators and clocks always look great. Akafugu has polished his IV-18 8 digit based VFD clock which also comes as kit that can be assembled without a drop of solder.
Clock is based on LPC1347 ARM Cortex -M3 microcontroller. It comes in two options, with or without GPS. The clock has all basic features you would expect including battery backup, alarm, optional GPS which is used to set time automatically, seconds can be counted with four different letter words. Project is based on open source firmware which can be hacked with your specific needs since there is plenty of memory and processing power left. Source is developed with mbed online ide and compiler.
In many cases oscilloscope is used to test low voltage and low frequency signals. This is what any low end oscilloscope is capable of. I think that proper oscilloscope should be on every hobbyists bench. But still there might be various reasons not to have. As quick fix to this problem might be a DIY solution. Tomeko have build really minimalistic scope project on STM32F042 ARM Cortex microcontroller. It accepts single channel, single voltage range signals and streams it to PC via USB FS with libusb as driver.
Scope’s sampling frequency is 480kSps at 8-bit resolution. Signal is captured in real time Windows application which can record signal to file up to 512M samples. This is enough for simple measurements and monitoring. The great thing about this is that circuit is really minimalistic with only few passive components on it. Because of this simplicity, it will never replace any oscilloscope, but it could find its use simple signal debugging is required. In other hand it can serve as additional module in some project where you might want to have a clue about signals inside. If you build it with home technologies it becomes really cheap.