Picture of PCB agitator from an old CD ROM

PCB making it's a really exciting thing, but when you need to etch, it will be boring if you use ferric chloride (in average it takes 20-30 minutes to be ready). During this time you need to agitate it to speed up the process a bit, but you also need to take care that the ferric chloride didn't spill out.

In this instructable I will present how to build an automatic agitator from an old CD ROM drive quite simply and low cost.
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Step 1: The old CD ROM disassembly

Picture of The old CD ROM disassembly
First, you need an old CD ROM drive which you need to disassemble carefully, not to break anything.

Step 2: Assembling the controller board

Picture of Assembling the controller board
You need some basic electronic components and an IC:

7x 4.7 kiloohm resistor
4x BC337 transistor or other similar
2x 100 nanofarad capacitor
1x 2 way pin header and socket
1x 3 way pin header and socket
1x 2 pin terminal block (PCB mountable)
1x small size (6x5cm) prototyping board
1x 4017 decade counter IC
1x socket for the IC
Some wires

Note: put the IC in the IC socket to avoid damaging by thermal shocks.


When the device is turned on, the IC Q0 output will be active, and the motor starts to spin to a direction. If the limit switch is pressed by the tray, the IC receives a pulse on its CLK pin and the Q1 output will be activated. The motor changes its direction and it keep this direction until the tray reaches the other limit switch. This switch sends a reset pulse to the IC and the Q0 output will be activated again and the motor changes its turning direction again. This cycle is repeated until the agitator is turned on.

ppsailor1 month ago

Hi !

My project

No microcontrollers

NO Arduino

mzsolt (author)  ppsailor1 month ago

Simple and clever project!
Thank You for sharing!

J-Five1 year ago
Okay, I misread it I thought it said "alligator".
g4dpf2 years ago

Pls could you tell me why you have R1 and R2 in parrallel on the clock input ?
I have built this and struggling to get it working

Thanks Iain
mzsolt (author)  g4dpf2 years ago
I wrote this instructable almost two years ago, and I don't remember the exact cause of the two parallel resistors. I checked my project, and the schematic is the same as the circuit, that I built. It should work.
Two suggestions: check your IC datasheet for pin out, and try to put a big(at least 1000uF) filter capacitor on power input.
If you have any questions, please ask me.
rimar20003 years ago
mzsolt (author)  rimar20003 years ago
Thank you!

I tried to present something useful and easy to build.
you made hack-a-day
Maybe mzsolt is same person that Mike Nathan. Otherwise, that is plagiary!
mzsolt (author)  rimar20003 years ago
No, I'm not the same person with Mike Nathan, my real name is Molnár Zsolt: "Instructables user [mzsolt] ...".
So, sorry. The dates (your response to kill-a-watt) clarify the issue...
mzsolt (author)  rimar20003 years ago
Never mind. It was only a misunderstanding.
mzsolt created the instructable on July 16th

Mike Nathan covered mzsolt's instructable in a post, saying it was a neat project. That's like the 2011 version of being slashdotted circa 1997.

I clicked on the link in the blog story over at hack-a-day and came here.

When  I said that he "made hackaday", I meant that he "was featured on the front page of hack-a-day".

So sorry for the misunderstanding.
mzsolt (author)  kill-a-watt3 years ago
So sorry, I didn't speak English as a native language, and I didn't knew this meaning of this word.
mzsolt (author)  kill-a-watt3 years ago
I didn't made Hack-a-day. Just check the publication date of my instructable. It's July 16th and the Hack-a-day article was published on July 17th.
woundup3 years ago
Hi try to make an PCB agitator out of an old CD ROM diive,but couldn't make it work,the tray would come out but not go back in again,try anorther CD ROM diive same thing happen, must to do with the switches or is the circuit right ?maybe it's a race between the cp0 and the reset,any thoughts please.
mzsolt (author)  woundup3 years ago
Hi! You have a bidirectional limit switch or two normal limit switches? You can try to reverse the motor polarity. If it doesn't work, try the H-bridge without the IC.
Nice! And very ecologically responsible. I got to build me one of these!

If I could add a bubble etch system to this and a temperature control and heater system, it would etch even faster!

Where are my crayons so that I can get to designin'?

Inspired, my friend, truly inspired!

mzsolt (author)  MatchstalkMan3 years ago
Thank you!
static3 years ago
Far out, a good idea, good indestructible. I think you meant to say turned off here " until the agitator is turned on" But I think I'll go with the more soothing sound of an air bumbler etching tank. Also the motor reverses in normal operation of the CDROM player. There should be a [H bridge] within the unit already. Any reason you didn't employ it, or was it just easier make one yourself,not messing with hacking into the units electronics?
mzsolt (author)  static3 years ago
I wanted to build a universal motor driver, because in some cases it's really difficult to find the driver IC datasheet.