Breadboards

Post by **spot** » Mon Jun 12, 2017 7:00 am

I looked on eBay to see what exists to teach basic electronics and it's all there, all from the Far East, all extremely cheap.

The best bit is the header power supply, it's the MB102. For under Â£3 you can have one delivered, with a 400-hole breadboard and pin-ended patch wires. The supply switches between 3.3 or 5 volts and easily provides a stable quarter amp drain. It can take power from a 6V or 12V PSU, battery or USB lead, and it's short-protected.

One turned up here with a few resistors, capacitors, diodes, LEDs, toggle buttons, some IC sockets and op-amp chips. And a few variable resistors. The entire parcel was less than US$20 and none of it involves soldering. I thought if there was a thread then those with an interest could drop the occasional photo here.

From what I can gather, the MB102 is a standard tool in Chinese school classrooms which accounts for the volume produced and the consequent low price. I think they'll have some far better educated citizens than us a few years down the line, the supply factories must be making these modules by the tens of millions.

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gmc · Post by **gmc** » Mon Jun 12, 2017 8:24 am

I have an interest but know bugger all about it, I really fancy building my own computer and installing linux but any hardware problems and I wouldn't know how to establish there was actually a problem with hardware and not software.

Bruv · Post by **Bruv** » Mon Jun 12, 2017 9:00 am

I buy ready sliced.

Bruv · Post by **Bruv** » Mon Jun 12, 2017 9:09 am

gmc;1510128 wrote: I have an interest but know bugger all about it, I really fancy building my own computer and installing linux but any hardware problems and I wouldn't know how to establish there was actually a problem with hardware and not software.

If you know as much as you say I wouldn't bother.

Compatible parts being the major drawback I think.

Get a barebones and fit the extra bits yourself........I have done it once and was well pleased with myself.

Think you have to fit the Hard drive and Optical drives yourself if memory serves me.

Wandrin · Post by **Wandrin** » Mon Jun 12, 2017 1:23 pm

I've used them for years for tinkering with various little projects or ideas.

I'd like to see them used in US classrooms since electronics are an integral part of life these days.

Post by **spot** » Mon Jun 12, 2017 2:08 pm

The first Integrated Circuit I was paid to build a circuit round was a UA741 8-pin DIP which I made the core of a furnace thermostat. I was paid to build the furnace too, and grow single-crystal zinc electrodes in it. That was in 1971. I might try to find today's 5 volt equivalent to work with, it was a pretty universal tool wherever an op-amplifier was needed so long as the frequency was within bounds, which would be zero to ultrasonic. They'd only been in production for a couple of years when I first used one and they were like science fiction turning real.

Wandrin · Post by **Wandrin** » Mon Jun 12, 2017 3:57 pm

spot;1510138 wrote: The first Integrated Circuit I was paid to build a circuit round was a UA741 8-pin DIP which I made the core of a furnace thermostat. I was paid to build the furnace too, and grow single-crystal zinc electrodes in it. That was in 1971. I might try to find today's 5 volt equivalent to work with, it was a pretty universal tool wherever an op-amplifier was needed so long as the frequency was within bounds, which would be zero to ultrasonic. They'd only been in production for a couple of years when I first used one and they were like science fiction turning real.

That sounds pretty cool. It must have been fun to design/debug.

Post by **spot** » Mon Jun 12, 2017 5:53 pm

I remember soldering the board, I had a 240v transformer bringing the power down to 12v and a rectifier bridge to get DC from it and I'd been testing the circuit as far as it had got. The back of my hand touched the 240v side and numbed my arm, which then fell back onto the 240v and I was hit a second time. Several arm shakes later I'd worked out what I'd done and I was annoyed with myself, to the point where I carried on soldering. For some reason I hadn't actually thought of switching off the transformer and pow, I did it again. That's the only time I ever had three mains shocks in one minute. I don't recommend the experience.

magentaflame · Post by **magentaflame** » Tue Jun 13, 2017 1:54 am

Remember in the eighties when you built your own computer?

Remember in the early 20th century when you built your own radios?

Post by **spot** » Tue Jun 13, 2017 6:59 am

I've built radios pretty much from scratch, yes. As far as computers go, I've assembled some.

Here's what I was looking for online. 4 op-amps on each chip, any DC supply voltage from 2.8v to 33v, 20 units delivered for $3. I'll see what I can make them do.

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Wandrin · Post by **Wandrin** » Tue Jun 13, 2017 8:46 am

spot;1510141 wrote: I remember soldering the board, I had a 240v transformer bringing the power down to 12v and a rectifier bridge to get DC from it and I'd been testing the circuit as far as it had got. The back of my hand touched the 240v side and numbed my arm, which then fell back onto the 240v and I was hit a second time. Several arm shakes later I'd worked out what I'd done and I was annoyed with myself, to the point where I carried on soldering. For some reason I hadn't actually thought of switching off the transformer and pow, I did it again. That's the only time I ever had three mains shocks in one minute. I don't recommend the experience.

I know what you mean. When I was a youngster with a new ham radio license a couple of folks gave me some old equipment -- all I had to do was fix it. One of the items was an rf linear amplifier with vacuum tubes. I don't remember how many times I brushed against the tube caps on top and got a ~400vdc jolt. The first time it knocked me off my chair.

Wandrin · Post by **Wandrin** » Tue Jun 13, 2017 2:49 pm

I'm finding that most of my little electronics dithering projects for the past couple of years have involved connecting a breadboard with an Arduino or Raspberry Pi.

Post by **spot** » Tue Jun 13, 2017 7:21 pm

Those are big grown-up computers.

There's a new kid on the block, the BBC micro:bit. One supplied free to every K7 student in the UK annually from this September, apparently. For the likes of me eBay carries them at US$16 including a battery pack to run them off-road, so I have two at the moment.

Why would some scrubby school-geek want to carry this particular programmable pocket computer, I hear you ask. Because it has embedded sensors and a display, that's why, and it's only half-credit-card size. It has a built-in magnetometer, 3-axis accelerometer, bluetooth, two thumb-input buttons and a 5x5 LED grid for display. And you can crocodile-clip your breadboard onto three wide I/O ports, or use a US$4 patch-panel to take all 20 connectors straight onto the breadboard for complete enjoyment where you can interface to all those dinky Arduino sub-boards for things like GPS and music synths and such.

It's the 5x5 display grid that makes it different, one could write some pretty good games for two thumb buttons and a grid like that. I haven't got as far as bluetoothing two of them together and writing a 2-person game but it's all in there. That onboard accelerometer means you could even point-and-shoot.

I quite like the drag-and-drop web programming page. K7 students being functionally illiterate can avoid all their spelling mistakes, and it shows the complete API to choose from in menus. There's also text-edit Javascript and Python options.

Wandrin · Post by **Wandrin** » Tue Jun 13, 2017 11:32 pm

I'll have to check it out.

Post by **spot** » Wed Jun 14, 2017 10:30 am

Here we are then, the new kid on the block as programmed and wired by the local six year old.

He's been talking for a week about "can we program that game", I know which game he means and this isn't it but what's here isn't a bad start. He shaped the X in the On Start paragraph, and he shaped an A on the grid for On Button A and a T for On Button B, pressed "compile" and copied the hex file over, and his breadboard buttons worked.

I suppose that means I have to draw a picture program for his game and let him drag-and-drop it into existence, I don't think he can break a task like that down on his own. Count how many raindrops you can steer down the grid before one touches an obstacle. Quite possibly addictive.

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Wandrin · Post by **Wandrin** » Wed Jun 14, 2017 1:23 pm

Looks like it could be fun.

Post by **spot** » Thu Jun 15, 2017 2:19 pm

This is drag-and-drop programming, something I've never seen before. The lad and I designed it this evening, it's a raindrop running past smudges and you can nudge the raindrop right or left, if you get to the bottom of the screen you win another go. We took turns with the drag and drop thing but I did the variables and chose what to drag next.

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Wandrin · Post by **Wandrin** » Thu Jun 15, 2017 7:39 pm

I've never seen drag-and-drop programming before, but I recall an article mentioning that it was a good way to get very young kids started with computers.

Post by **spot** » Fri Jun 16, 2017 12:18 am

If you saw Randy Pausch's Last Lecture, he was at the centre of developing the approach with a storyboard system called Alice and getting it used in schools. Ten years back... it doesn't seem that distant.

Post by **spot** » Mon Jun 19, 2017 6:36 am

After exposure to several Airfix kits, Jowan populated this board last night on his own except for the DIP holders (the legs needed synchronizing) so he's definitely getting there. No polarity errors at all. If he manages the soldering tonight I'll add a photo of the other side.

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Post by **spot** » Mon Oct 28, 2019 11:57 am

I found his light cascade from the previous post just now, it still works.

This is Jowan's soldering desk this evening, I thought I'd keep the thread moving. The breadboard has his demonstration of logic gates, the TTL computer is the Gigatron kit and comes with a homegrown machine code which, the designers hope, will run 6502 in emulation by the new year.