Steampunk Electronics–Heartbeat Part 4

The Home Made PCB

Today I made my first home made printed circuit board. The challenge was to design the and etch a circuit board.
I decided to use the Hydrochloric acid and Hydrogen Peroxide etchant.
I had previously designed the circuit using Fritzing and then printed it out on plain 80gsm copy paper. I had heard that this wasn’t ideal, but what the hell … we are just prototyping, so whatever.
I used the iron on Linen (the hottest setting for our iron) and pressed the design onto the copper clad board. Next, I bathed the copper clad board in water to get the paper off.
Things looked pretty OK at this stage, the print transfer was not too bad, I could see some pitting under the magnifying glass. But … let’s see how it goes. I decided to use my Sharpie pen to improve the lines somewhat.
I made the etchant from 1 part Hydrochloric acid mixed with 2 parts Hydrogen Peroxide. I bought a 200ml bottle of 3% Hydrogen Peroxide from the chemists and a 500ml bottle of Hydrochloric acid from the hardware store. I also bought some Isopropyl alcohol and some nail polish remover so that I could clean the board once it had been bathed.
Before doing anything, I got some glasses on and put on my heavy duty rubber gloves. I also prepared my work surface, putting down a 1m x 80cm plastic mat to protect the table.
I poured the 200ml of peroxide into a clean and empty orange juice bottle and then measured out 100ml of acid and poured it into the bottle and gently agitated it.
Next, I poured a small amount (about 100ml) of the solution into a smaller plastic container and then I put the copper clad board into the solution … then I waited.
About 10 minutes later, I had a nice looking board with all of the copper dissolved away, leaving the black laser toner and Sharpie ink.
I took a tissue and rubbed the toner and ink off the board and then gave it the once over with the rubbing alcohol to be sure.
The result was quite reasonable … it still looked a little pitted in places, but testing the board with my multimeter showed that the traces were not broken. I used the multimeter in continuity mode.
Then, I got out the components to solder to the board, the soldering iron and the solder and fixed the components onto the board.


Sorry about the poor quality of the pictures.
Then I powered it up and got … nothing.
The step that I missed, the step that I should not have missed, the thing that I failed to do in my impatience to go from design to circuit board was … relaying out the prototype board with the changed design. Now I need to go back to the drawing board and do it all over. Still, that’s not that much of a problem, it is fun and it’s a learning experience.

Steampunk Electronics–Heartbeat Part 3

Well now … I have duplicated the circuit that Charles Platt shows in his book.

The circuit makes use of direct component soldering rather than using jumper wires or using routes from a printed circuit board.

The resulting circuit works fairly well, although I believe that the capacitors are shorting somewhere in the circuit as the LED does not pulse as the prototype board version did, rather, it pulses on and flashes off. When the power is removed from the circuit, the LED powers down completely, without any capacitor leaking.

Anyway, this is a prototype and I am working on that basis.

As you can see from the picture, the circuit is very small.

You  can see from  the under side, that the legs from each component is used to connect to the next component(s) in the circuit.

I am using some very cheap circuit boards that I bought from eBay. I neglected to clean the board first, so the soldering job wasn’t all that successful (part of the reason that I think that there is a soldering fault). However, as the components are directly soldered, the perf board is used merely as a strata for the circuit.

And here it is.

I need to make a printed circuit board next to improve and refine the prototype.

Steampunk Electronics–Heartbeat Part 2

In the first article, I was talking about using the Charles Platt design for creating a pulsing LED using a 2N6027 PUT, a couple of resistors, a couple of capacitors and an LED.

Today, I took the schematic from Make: Electronics (by Charles Platt) and built it on a prototype board.

The first thing that I did was to transfer the resistors from the schematic onto the prototype board. It’s a simple design with not many components, so I decided to have the resistors spanning the separation channel in the middle, and then use jumper wires to connect them all.

Next, I put the capacitors  in place along with the transistor and the LED.

Finally, I jumped the components so that they were connected according to the schematic.

I connected the battery (9V) to the board and waited … and waited. There was something wrong.

I needed to get out the multimeter and work out what was wrong.

I tested the battery … it was measuring 8.94V so that wasn’t the problem. Next I tested continuity on all of the jumpers … they were working fine.

Test the resistors, also OK. Interestingly, the resisters that I bought from eBay … all within the stated tolerance, so, Yay.

Test the capacitors … also fine.

I tested the LED and it was also peachy keen … so what had I done wrong?

I noticed that the prototype board power rails had a break in the middle and that I needed to jump between the gaps (d’oh!) I should have realised that this was the case, but then, this is the first time that I’ve used the prototype board in earnest.

After putting in the jumpers, I powered it up and … presto! it works just like is says on the box.

I’ve colour coded the jumpers so that I know what is going where.

White jumpers connect to a resistor, Green jumpers connect to a capacitor, Blue jumpers connect to the transistor, Yellow jumpers connect to the LED. Black and Red are Negative and Positive power respectively.

I’ve just been playing with the circuit a bit and I’ve decided that the timing for the LED was wrong. The LED flashed too quickly for my taste with a cycle of on-off in about 1 second. I’ve replaced the capacitors in the circuit. Now the capacitors are:

C1 – 220 µF electrolytic capacitor; and

C2 – 470 µF electrolytic capacitor.

The on-off cycle is now about 2.5 seconds and much more pleasing for me.

Next, I’m going to transfer this to a perf board and put it in a project box. I think that this will work well for the Steam Punk prop. The prototype perf board will be larger than the one that I will use with a PCB, simply so that I have space to wire it. I will be using a standard copper padded perf board and the holes are all pre-drilled, so there won’t be much opportunity to compress the design. Also, because I will be using wire between the components rather than copper route, I will need some extra space for soldering and general jiggery pokery.

Anyway … it’s time to go and play with perf board and project boxes.

Steampunk Electronics–Heartbeat

I’ve been playing around with making a pulsing LED that I will use in the body of the Steampunk gun. The LED will be mounted in the back of the gun and I will make a resin shell that will go around it … kinda like a dome on the back of the gun.

The circuit is basically a series of resisters, a couple of capacitors and a 2n6027 PUT (programmable unijunction transistor). The arrangement of resisters and capacitors shape the voltage through the circuit so that the first capacitor takes a short while to charge up, and then leak out. The result should be a gradual increase in the light emitted from the LED and then a slower decrease in the light.

I’ve seen some circuits on the interweb that use a 555 timer IC (integrated circuit) to do the switching from on to off, but this one from Charles Platt (Make: Electronics) is much more straight forward and should do what I need it to do. Plus … this circuit is cheaper than a circuit using a 555 timer.

I’m using a pin header for both the power connection as well as the leads for the LED so that I can have the LED on a flexible connection. I’m fitting the connecting wires with 2 pin DuPont female connectors so that I can easily connect the battery (9v) and the LED.

Parts:

• C1 – 100 µF electrolytic capacitor;
• C2 – 220 µF electrolytic capacitor;
• J1 – Generic female header – 4 pins;
• LED1 – pick whichever you like … I’m going to use a 5mm white ultra-bright 20000mcd that I picked up on eBay from (vendor bobpwaytoway);
• Q1 – PUT Transistor 2N6027;
• R1 – 33k Ω 1/4W 250V Through Hole Carbon Film Resistor;
• R2, R3, R4 – 1k Ω 1/4W Metal Film Resistors;
• R5 – 330 Ω 1/4 W Metal Film Resistor;
• VCC1 – 9V battery block;
• FR7 single sided copper clad board.

After jiggering around with the circuit for a while using Fritzing, the above PCB is the design that I’m most happy with.

The top two pin of J1 are connected to the battery. The bottom two are the LED.

I’m going to mount the LED in a ping-pong ball so that the light is more diffuse.

I’ll prototype the board this weekend and post any updates and photographs.

You can see that this is a very simple and small circuit, so it won’t take long to prototype or solder. I’ll make an intermediate prototype using perf-board so that I can see how the rats nest works out for me. The board is about 4.5 x 3 cm so the size should suit my needs too.

Steampunk Firepower–Electronics

I bought some lighting electronic kits from an electronics store that perform some of the lighting jiggery-pokery that I want to put into the Steampunk props, such as the flashing light and chasing lights.

These are not particularly difficult or complex circuits and they fall within the ambit of my level of skill with electronics (i.e. not much).

The kits were pretty cheap ($7 – $15) and the printed circuit boards are very paint-by-numbers so it wasn’t very hard to build them.

Here is the chasing lights circuit, the red LED light up left to right and then right to left continuously. In the Steampunk prop, the LED will be mounted around the barrel when the trigger is pulled.

The flashing light circuit simply oscillates between the green and red LED. In the prototype, the lights will be mounted in the body and be viewed through a bunch of resin ports in the side of the gun.

The next trick is to duplicate the printed circuit in a wired circuit so that I can make sure that I understand the circuit properly. I also need to be able to change the shape of the boards so that they fit into the prototype better and run from a single 9V battery.

I’ve ordered all of the components that I need to be able to build these circuits, and I will make some modifications to the design by including some trimmer potentiometers (so that the frequency of flash and speed of chasing lights can be tuned). I’ll make these on the prototype board first and then transfer the design to a strip-board PCB.