Velleman MK105 Signal Generator - assembly – House of Hacks

Friday, November 8, 2019

Velleman MK105 Signal Generator - assembly


Description

Interested in basic electronic kit projects? In this episode of the House of Hacks, Harley assembles a Velleman Signal Generator kit MK105. This kit is moderately easy to assemble. The company rates it as a 2 out of 5 on the the difficulty scale. Soldering is required but is probably a good kit for learning how to solder circuit boards.

Velleman MK105 Signal Generator (affiliate link)

Soldering station review
How to solder
Soldering tips

Tools needed:
Soldering iron or soldering station and solder
Needle nosed pliers
Wire cutters
Panavise or 3rd hand

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For a written transcript, go to Velleman MK105 Signal Generator - assembly

Music under Creative Commons License By Attribution 4.0 by Kevin MacLeod at http://incompetech.com.
Intro/Exit: "Hot Swing"
Incidental: “District Four"

Transcript

Today at the House of Hacks, let's assemble this signal generator.

If we're just meeting, Welcome!

I'm Harley and I make stuff in the workshop, usually out of wood, metal and sometimes electronics.

This is a basic electronics kit made by Velleman. It's a signal generator model number MK105 and we'll be assembling and testing it today.

It runs off a 9 volt battery and makes sine waves, triangle waves and square waves at about 1000 hertz.

Inside this kit... there's the card that holds everything in,

a battery holder,

a bunch of components in a plastic bag,

and a PCB.

Inside this card is assembly instructions and a schematic. We'll get to those later.

The first thing you want to do is dump the parts out and separate them into their different types of components.

These are resistors and they have color bands on them to identify them.

These can looking things are electrolytic capacitors.

These flat disc looking things are regular capacitors are non-electrolytic.

This is a jumper. These are header connectors for the jumpers.

This is a socket for the chip and here's the chip itself.

Here is a variable resistor.

And some plastic stand-offs and screws to mount this. This will get mounted to this when it's all said and done.

Looks like there's a transistor here with three legs. They're kind of an interesting shape. They're usually a dome with a flat side on them.

And those are all the different pieces parts.

And then there are these connectors that will be the ground and output for the signals.

I think that's everything in here. We'll just separate these out and put them into piles. We'll separate the resistors by component values.

And there's a diode too. It looks kind of like a resistor. Rather than having the color bands on it like the resistors have, it has a number around it that tells you the component value and also it has a single band that tells you which direction it goes in the circuit. That is important.

So it looks like there are... one... two... three... four... five values of resistors. Three different values of capacitors. One value of electrolytic capacitors. A single value for the transistors. And there's only a single diode so there's only one of those values.

When we're putting in capacitors we need to be sure to put these in the right places because they do have different values on them and along with the resistors.

The electrolytic capacitors, we need to pay attention to their polarity but it's the same value for both of them.

And the same thing goes for the transistors and diode.

This is the card that holds all the components in the blister pack and inside here are all the instructions. They're actually laid out really well considering there's not really any writing on them. They're all just illustrations.

Across the top it shows how to put the pieces in for soldering.

And then it tells you what to do.

Generally with electronics kits, you want to start from the smallest components and work up to larger components.

That way you're not trying to fit small pieces down in between larger pieces.

This follows that same convention.

We have the resistors are number one. And this is also very well laid out because it has the numbers for the resistors which are marked on the PC board and the values for the resistor here but over here they're actually telling you what color represent those values.

So you don't even have to look it up. Whenever it says R1 through R3, use the brown-black-red resistors.

And when you need resistors R4 through R6 you use the brown-black-orange resistors. And just so forth. Very well laid out.

Then we put in the diode and then the IC socket and the IC iteself and the transistor, the capacitor, electrolytic capacitors, the potentiometer, the jumper, the test points that have the output and the ground.

We'll put in the battery connector and then it shows how to put the jumper in to get different wave forms and finally there's a schematic that shows have everything is put together.

Today, I'm going to just be assembling and testing this. Leave a comment below if in the future you'd like to see this either put into a project box or talk about the theory of operation.

This is a good, easy beginners electronics project. The only real specialty tool you need is a soldering iron. I've got a temperature controlled soldering station. It's kind of a low to mid-range tool but you don't need anything near this fancy. You can use just a simple pencil soldering iron that's not temperature controlled for this particular project.

Those can be had for less than $20, I'm sure, and that'll work just fine for this.

You need a little bit of solder for connecting things together.

You'll want a fan to blow across the project to keep the solder fumes from rising up into your face.

I've also got some needle nose pliers to bend wire leads with and wire cutters to trim those leads with.

And then you need a place to work. I'm using a Panavise tool that's designed specifically for working with circuit boards.

But you don't need anything near this fancy. Just working on a flat table top, probably want to protect it with some cardboard or something that would work fine. Also, if you need to hold the circuit board, I've use pliers with a rubber band just to hold things and that works well too if you need it at an angle.

And if you're of a certain age, reading glasses. We will be working in close.

Let's get this put together.

[music]

OK. When working on these, we want to bend these leads down so that they fit into the holes like so.

And then we find the location on the circuit board that they go in. In this case, this is R8 and R8 is... right... 11... 9... 10... R8 goes right in here so we'll just put this right in here like so.

And on the back, we'll just bend these leads over, that'll just hold it in place before we get the solder in.

[music]

OK. So that does it for the resistors. We've got the diode and the rest of the components to put in. It's all exactly the same process and we'll just work through all of them.

OK. Here we're putting in the diode and we can see on the printed circuit board there's this heavy bar on the one side of the outline for the diode. That indicates where the bar that's on the diode itself should go in the orientation so you make sure that gets put in there correctly.

Also, we can see on these electrolytic capacitors, there's a plus side to indicate where the plus goes on the capacitor and also on the transistor, there's a D shaped outline that corresponds to the flat side we saw on the transistor earlier and finally on the integrated circuit, there's a notch indicated on the printed circuit board. So those all need to go in one particular direction and it's important to watch the orientation. For the other resistors and the other capacitors, they can go in any direction you want.

[music]

It came out to be a pretty nice little package. I do need to find a 9 volt battery and then we'll take it over to the bench and turn on the oscilloscope and see what the output looks like.

[music]

I found a 9 volt battery. Pulled the oscilloscope out and got it warmed up. This is an old CRT one so it takes a little bit to warm up.

And got everything connected and we can see we have a fairly nice square wave here.

It does drift a little bit. It's a little bit faster than a 1000 hertz but for a basic signal generation to make audio checks and things like that it's fine.

It does have some other settings.

It has what they call an integration setting which we can see here. It's sort of a weird looking signal.

And then it has a triangle wave which looks pretty nice.

And finally there's a sine wave.

And the little trimmer pot adjusts the voltage so we increase the voltage and decrease the voltage if we want.

So that's not a bad little kit for a couple dollars.

Easy to put together. Great beginner kit.

Over here there's another video that YouTube thinks you'll enjoy.

Until next time, go make something.

Perfection's not required. Fun is!