Voicetron - Voice Recording Toy

This device was created for pleasure and inspiration for anyone who would like to make a simple voice recorder for their children to play, or as a decoration, or use in Geocaching or in escape rooms. There are many possibilities. So let's get to it.

Let's start with the toy concept. The device must include a microphone, loudspeaker, recording module, a switch and control buttons, and some decorative elements. All in a battery-powered box. I decided to use the ISD 1820 module, cheap and easy to find on ebay. The 9 volt battery needs an intermediate circuit, which will be a simple dc-dc converter to 5V. The second figure outlines two variants of the arrangement of individual components and parts.

• 1x ISD1820
• 1x 9 Volt battery
• 2x Push button
• 1x Toggle switch
• 1x DC-DC converter
• 9 Volt battery clip
• 1x 47ohm resistor
• 1x 470k ohm resistor
• 1x 2n3904 npn transistor
• 1x 5V Light bulb
• 24 Awg stranded wires
  
• Heat shrink tubes
• Soldering Iron
• Soldering solder
• Cutting pliers
• Needle nose pliers
• Cutting pliers
• Acrylic paints (silver, brass / copper)
• Screwdriver
• Multimeter

I decided to use an old speaker, which lay unused for a long time. Its dimensions seemed satisfactory and it was also quite robust. Features a built-in speaker and front metal mesh.

I liked the idea of placing the microphone in a long, flexible tube that could be shaped as needed. I got inspiration in the dollar-store when I saw this lighter. I disassembled it and kept the metal flexible part and also the metal cylinder that formed the end of the lighter.

I made a socket for a light bulb with a piece of copper wire. I wrapped it around the thread of the bulb and then pressed it with pliers a little to make a good conductive contact.

I created the ornaments using a 3D printer. I wanted to achieve a slight steampunk touch, so on the one side I created a hole for a switch and a slot for a decorative fuse and on the other I formed something resembling a tank, which will later be connected by a spiral coil with a recording button.

The recording button will be secured with a cage to prevent unwanted recording.

The upper part will contain holes for a light bulb, a microphone tube, a small antenna and one push button. The bulb will be placed inside the protective cage.

I used copper acrylic spray to paint the box. The spray creates a uniform color that is suitable for smooth and larger surfaces. Ornaments printed on a 3D printer will be colored with a brush. The front part is covered with masking tape to keep its original color.

I applied more coats as I touched the non-dried paint too soon and ruined the first coat. In some places, the paint was also sprayed unevenly.

I first covered the shiny part of the flexible tube from the lighter with masking tape. Subsequently, I sprayed both ends with matt acrylic black paint and then applied lacquer.

Before drilling the holes, I unfolded the printed parts on the appropriate sides and arranged them so that I was aesthetically pleased with them. Subsequently, I marked the holes to be drilled and drilled them with a step drill bit and a small drill.

The inside of the box is large enough for a 9 V battery, which I placed in the upper corner and placed the printed circuit boards on the back cover. I fastened them with the help of spacers, which I attached to the cover with the help of a hot air gun.

The remaining empty space of the box will be filled with wires.

I screwed in both buttons and soldered one pair of their legs together, which will be connected as a common anode.

First, I treated the contacts with rosin, for better adhesion of the soldering solder. I used a yellow wire for the common anode and blue wires for recording and playback. After soldering, I secured them with a tube and then twisted them to make them easier to handle.

The switch serves as the main switch. It allows current to flow from a 9 V battery to a DCdc converter.
When it is turned off, we will not spend any energy even on the standby run of the converter.

It is necessary to prepare wires for the microphone. These will later run along the entire flexible tube, so they need to be a little longer.

The socket of the bulb will be inserted through the 3d ornament in a later step, so we will also prepare the wires in advance.

Solder the red wire leading from the switch to the + terminal and the black wire directly from the 9 V battery clip to the - terminal of the DCDC converter. I tinned the contacts first to make better contact.

To set the output voltage of the DCDC converter, we will need a multimeter. After connecting the battery and turning on the switch, we measure the output of the converter. With the help of a small screwdriver, we turn the trimmer (try both sides) and thus adjust the output voltage to a value of about 5 V.

The datasheet of the ISD1820 module tells us that the resistor connected from the Rosc pin (pin 10) to ground defines the sampling rate of the recording. With higher sampling, the recording time shortens, but its quality is higher.

In this step, we adjust the default value given by the manufacturer, which is 100k ohm (resulting in 10 sec recording duration and 6.4 kHz sampling rate), to a value of approximately 80k ohm. This achieves an 8 kHz sampling rate, ie higher sound quality. To change the value of the 100 k ohm resistor, add a 470 k ohm resistor in parallel.

We need to add a transistor that will work as a light bulb switch. First, connect the emitter of transistor 2n3904 to ground. Then we connect a 47 ohm resistor between the positive speaker pin (red) and the base of the transistor. The bulb will be connected later between Vcc terminal (5 V) and the collector of the transistor as shown in the figure.

We will connect the output from the dcdc converter to the input ISD1820. It is possible to solder the wires to the front directly to the connector or to the back side of the pcb.

We need to remove the microphone soldered directly to the module so that we can later insert it into the flexible tube. Before desoldering, I first treated the contacts with resin. Subsequently, I soldered two wires to the terminals where the microphone was, which I had prepared before.

Connect the wires leading from the buttons, the common anode (yellow) to the Vcc terminal (5 V) and one wire to the REC button, the other to the PLAYE button (both are blue).

I connected two wires (white & brown) between the positive terminal of the Vcc and the collector of the transistor, which will later lead to the bulb. Polarity of the bulb does not matter.

Depending on the print quality of your printer, you may or may not have to sand decorative parts. For sanding, I used a set of files and also a small grinder.

I used the cutter to remove excess printing defects (like stringing).

I wanted the toy to have a steampunk touch, so I decided to paint the ornaments in silver. You can use an antique hobby paint or a regular acrylic spray paint. I sprayed a little acrylic paint into the lid and painted the parts by hand with a brush, for more detail.

After the printed parts had dried, I glued them to the surfaces of the box with a quick-drying glue.

I pushed the longer pre-prepared cable through the flexible tube and soldered the microphone to the end, secured with tubes.

To attach the microphone, I applied a little glue and then put the original lighter cover on the flexible tube. The masking tape will be removed at the end to avoid scratching the paint.

Before soldering the bulb, I sanded the inside of the socket to make good conductive contact. I also ground the end of the copper wire of the sleeve so that it could be soldered.
Then I connected the wires leading from the module (brown and white) to the light bulb (polarity doesn't matter).

Those parts that will be exposed to mechanical stress (flexible tube with a microphone, switch and, for sure, a light bulb on which there will be a cover later), I secured with the help of hot glue.

I attached the metal grid, which was removed at the beginning, back to the box in this step. It is fixed with small bent handles inside the box.

The wires inside the box, I pushed into one corner. A 9 V battery was placed in the other corner.
closing the back cover. Twisted cables help with handling and do not fly everywhere.

I installed a protective cage for the REC button, which will have a functional (prevent unwanted recording), but also an aesthetic function.

In this step, I mounted a protective cage for the bulb. The cage is secured in the thread with a piece of bent wire.

On the ornament located on the right, I inserted a fuse. The fuse holds firmly in the holder and therefore I did not use glue.

I placed an old needle from the bicycle pump on the ornament placed on top. I secured it with hot glue.

On the ornament on the right, I wanted to attach a coiled wire in the shape of a coil. I formed it with a marker, around which I wrapped a few turns of copper wire, and then with the help of pliers I bent the beginning and end so that they could be inserted into the holes on the ornament.

Finally, the project is completed and ready for use in games, geocaching, escape rooms or recording for fun.

I'm adding a few extra photos.

If you have any questions, do not hesitate to contact me.

If you like the project, I will be happy if you vote for it. Thanks for reviewing.

Stay healthy and safe :)