[Ben Eater] is back with the second part of his video series on building a simple video card that can output 200×600 pixels to a display with nothing but a VGA connection, a handful of 74-logic chips and a 10 MHz crystal. In this installment we see how he uses nothing but an EEPROM and a handful of resistors to get an image onto the screen.
The interesting part is in how the image data is encoded into the EEPROM, since it has to be addressable by the same timing circuit as what is being used for the horizontal and vertical timing. By selecting the relevant inputs that’d make a valid address, and by doubling the size of each pixel a few times, a 100 x 75 pixel image can be encoded into the EEPROM and directly addressed using this timing circuit.
The output from the EEPROM itself not fed directly into the monitor, as the VGA interface expects a 0 V to 0.7 V signal on each RGB pin, indicating the brightness. To get more than three colors out of this setup, [Ben] builds up a simple 2-bit DAC that allows for two bits per channel, meaning four brightness levels per color channel or 64 colors effectively.
See the video after the link for the full details. While pretty close to perfect, a small issue remains at the end in the forms of black vertical lines. These are caused by a timing issue in the circuit, with comments on the YouTube video suggesting various other potential fixes. Have you breadboarded your own version yet to debug this issue before [Ben]’s next video comes out?
Continue reading “Pushing Pixels To A Display With VGA Without A PC”
Sometimes the most useful hacks are also the simplest ones. A case in point is the LED and resistor assembly that [Skippy] recently posted on his blog. The idea is to solder up some pre-made indicators with integrated resistors to save space on the breadboard when prototyping — instead of four slots, you only use two per LED. This is about as easy a trick as you can imagine, but it has the hallmark of a classic hack: a high utility-to-work ratio.
The deluxe assembly uses a two-pin header as a base to plug into the breadboard. This, of course, could be optional since some breadboards have a memory for the widest pin previously inserted — using header pins may eventually make the slots a little flaky for smaller component leads. But, if you’re mostly using header pins in the breadboard anyway, this is a good way to avoid kinking the leads.
While there are LEDs available with integrated dropping resistors, building your own means you can use whatever LEDs you prefer — or simply have on hand — and adjust the resistor value for different voltages or to adjust the brightness. And for those of you who plug in LEDs without current-limiting resistors, we’re going to assume that you’ve thoroughly researched whatever is driving them and done the math to ensure they’re safe. Or not: they’re your LEDs after all.
We previously featured a no-solder breadboarding trick for SMD LEDs. What’s your favorite solderless breadboard hack? Let us know in the comments below.
Thanks to [Roboteernat] for the tip!
Solderless breadboards are great for ICs and discrete components like resistors, capacitors, and transistors (at least the through hole kind). They aren’t so good at holding big components like potentiometers. Sure, you can jam trimmers in maybe. You can also solder leads to a pot, but that’s not pretty and tend to pull out when handled. [PaulStoffregen] got tired of it, so he put together some good looking PC boards that mount a 6mm shaft pot securely to a breadboard.
[Paul] noticed that having delicate or knobless adjustments on a breadboard inhibited people from playing with demo circuits. The new set up invites people to make adjustments. The pictures and video show an early version with six pins, but [Paul] added two more pins on the recent batch to increase the grip of the breadboard.
Continue reading “Breadboards Go To Pot”
[Chuck Stephens] grew up with Radio Shack 100-in-1 electronic kits. The ones with lots of components and spring terminals that could be wired to be a radio, a burglar alarm, or whatever.[Chuck] graduated to solderless breadboard, but did miss having panel mounted components like pots and switches easily available. So he has been building his own accessory boxes.
Of course, it is easy enough to just connect breadboard wires to component, but [Chuck] went further than that. Using boxes of different types (including a cigar box), he mounted the components properly and also wired them to a breadboard for easy connection.
If you’ve ever tried to solder to breadboard springs (we have), you’ve found it is hard to get adhesion to the shiny metal. [Chuck] solved the problem by crimping little wire hooks to the springs. The result is a good looking and functional prototyping aid.
They do make tiny breadboard style contacts (called tie point blocks; good luck finding them) for this kind of application, but the crimp technique works on common breadboards. These are cheap and much easier to find.
Of course, these days, we are as likely to want to mount SMDs than panel mounted controls. Now if we could only figure out where to put the components. If you want something less involved, take a look at the video below.
Continue reading “Panel-Mounted Breadboard Accessories”
If you like messing around with electronics, one of the best tools you can have on hand is a solderless breaboard. These handy little chunks of plastic just let you “plug n play” so you can quickly develop a circuit before committing it to solder and fiberglass. Handy as they are, they do have their downsides such as: stuff not fitting, split up power rails, running out of jumpers or just taming what can quickly become a birds nest of a mess.
Luckily the folks over at [Proto Stack] have published a handy article giving us 8 Breadboard Hacks. While anyone that has used breadboads for any length of time will have probably figured most of these out, its still good knowledge for any newcomers to the sometimes aggravating world of plastic and jumpers.
Also we know there are more hacks you can do to make your lives easier and would love to hear them in the comments.