Wednesday, June 23, 2021

555 Timer - LED Flasher with conductive 3D Filament - Astable Mode

June 23rd 2021

By Bits4Bots

 Rapid circuit prototype with a 3D printer and conductive filament. This project features a simple circuit designed to explain the working and use of a 555 timer IC. The connection used is credited to this blog LED Flasher Circuit 
 The 555 timer was one of the first IC chips I learned to use in a project back when I attended community college. I learned to read the datasheet and create my first flashing LED! This is a good place to start for those new to electronics. *I recommend reading the 555 timer datasheet to learn more!


3D printer
Proto-Pasta filament
eSun PLA filament
555 timer IC
5mm LED or similar i.e 3mm, 10mm
1uF capacitor - C1 * Can be SAT (selected at testing)
x2 resistors (1K) - R1 & R3
1 resistor (100K) - R2 *Can be SAT (selected at testing)
9V battery
9V snap connector

Download and print the 3D file(s) here or from Thingiverse I designed the assembly for one single print

(1hr 30min) or in two parts 45min each:

Base 30mm x 30mm
Traces for testing purposes (different Z-axis height layers for various conductivity)
For TinkerCad users see link: Tinkercad

Note: When the print is 7% to 8% complete, the conductive filament should follow. Here is a great Instructable for welding 3D filament Filament Fuser.

*I simply snipped off the colored PLA with a wire cutter, then guided the conductive filament into the 3D printer until the extruder accepted (grabbed) it.

After the print is complete the top layers of the board should have 3mm+ conductive filament.

Pin 2 and 6 are connected. All other pin connections will need to be made manually.

Place 555 timer onto 3D printed board and press firmly to make a strong connection. Careful not to bend the legs!

1. Connect pin 4 and 8 together with a male to male jumper or wire. *tinned wire for optimization
2. Connect LED ground leg to pin one.
3. Connect R3 (1K ohm) to +itive lead of LED, and then to pin 3.
4. Connect R1 between pin 6 and 7
5. Connect R2 between pin 7 and 8
6. Place C1 between pin 1 and 2 *-itive lead to pin 1 (for polarized capacitors)
7. Note: Pin 5 will not be connected (this is also called floating)

The last step is to power the circuit. 5V-9V is a good value to use for the power supply. Here I used a 9V battery and snap connector.

Connect negative lead to pin 1. Connect positive lead to pin 8

Please like, share, or comment. Find us on all social media! Check us out on Tindie

**Did we make a mistake? Let us know :)

Before we designed our 555 timer circuit we conducted a search for conductive 3D filament. There are several companies that you can choose from. We decided to go with Proto Pasta. The details for conductivity are below:

Volume resistivity of molded resin (not 3D Printed): 15 ohm-cm
Volume resistivity of 3D printed parts perpendicular to layers: 30 ohm-cm
Volume resistivity of 3D printed parts through layers (along Z axis): 115 ohm-cm
Resistance of a 10cm length of 1.75mm filament: 2-3kohm
Resistance of a 10cm length of 2.85mm filament: 800-1200ohm


Now that the resistivity is known the next challenge is to calculate the resistance in each trace used.

I measured 2k Ohms in the curved traces on pin 1 and on pin 8. These are the traces that connect the power supply.

The shortest traces measure 1k Ohms. Pin 4 and pin 5.

The trace from pin 2 to pin 6 is 1.5k Ohms.

The T-shaped trace, pin 3 (trigger) and pin 7 around 1.5k Ohms.

***Increased layers on the Z-axis = increase the resistance. Less layers can be used to best resemble standard wires such a copper or other metals presented in general printed circuit boards. This portion of the 3D PCB is a work in progress.

In addition, advanced users can accurately determine exact wire (3D trace) resistance via circuit simulation software that can perform line calculations i.e. NI Multisim, ADS (Keysight), and others.

Calculate LED Flash Time

For the 555 Timer IC you, the designer, will calculate on/off flash time. The link below is a great way to calculate your design or check your math work. 555 Astable Circuit Calculator


Increasing C will increase the cycle time (and hence, reduce the frequency).
Increasing R1 will increase Time High (T1), but will leave Time Low (T0) unaffected.
Increasing R2 will increase Time High (T1), increase Time Low (T0) and decrease the duty cycle (down to a minimum of 50%)
By hand you can use these formulas to calculate the LED time on/off in seconds.

Time high (on) = 0.7 * (R1 + R2) * C1

Time low (off) = 0.7 * R2 * C1

Monday, May 17, 2021

Hello Makers,

We are now adding 3D makes to our new Thingiverse page. See you there!


Friday, May 29, 2020

Paper Circuits - Blaster Rocket

Author: Larsha Johnson
Published: May 26th 2020

Experimental solderless LED kit for kids

Designed for kids who want to start building electronic circuits, with real components, without soldering.

In stock on Tindie

Paper circuits are low-power electronics that are created on paper utilizing conductive tape, LEDs and a power source such as a 2032 coin-cell battery.

There are small items used in this project such as LEDs and can be a choking hazard for children under 3 years.

  • Coin-cell battery (3V) CR2032
  • Copper tape (1/4″) with conductive adhesive
  • LED – 3mm, surface mount or similar 
  • Blank canvas card stock


  • Step 1: Insert the conductive tape through the canvas.

  • Step 2: Peel and remove the adhesive tape.


  • Step 3: Mount the 3mm RGB flashing led in the pin hole.


  • Cont' tape down the lead of the LED

  • Step 4: Glue the outline of your paper circuit to the canvas.

  • Step 5: Decorate the paper circuit. Add glitter, color, and any extra bells and whistles.

  • Step 6: Add the coin cell battery. Use tape to secure it as needed.

  • Step 7: Tape the rocket flame to the circuit to finish the project.

Enjoy the project and share with friends. 

For help please read the Troubleshooting section in the following link: Makerspace 

Thursday, April 30, 2020

Doodle Doggie Badge

Badge Life - DIY Doggy Blink Badge

DIY led puppy badge. White PCB in a puppy shape. DIY to wear. Try adding color. Customize it! Ruff ruff enjoy.

Wednesday, April 29, 2020

Turtle Proto

Turtle Proto

A solderable prototype board. 180 tie points. Ideal for electronic projects with micro controllers like
Adafruit, Arduino, Micro:Bits, Raspberry Pi and others. 

Buy now on Tindie Maker Marketplace

BREADBOARD General Purpose. Fun and unique turtle shaped tie-point prototype solder board. 8 SMD practice pads. 59mm x 79mm diameter.

Friday, July 5, 2019

Crabbie : Interactive Development Board for Kids K-5th

Updates soon...

Saturday, June 1, 2019


After a previous post we wrote about creating custom shields using the NI Multisim and NI Ultiboard, we have decided to try it again. Here is our version of a customized compatible MKR 1010 wifi. The dimensions are 61.5mm x 25mm. 28 header pins options and 4 mounting holes. This lightweight bare bones can take your project to the next level. Since the MKR 1010 provides wifi, bluetooth, li-po battery connection with charging & many I/O pins you will want to get your hands on our cool shields. Release date summer 2019. Contact us for pre-purchase.

Now about the Nano 33 Iot. Did you know Arduino is releasing four new boards this summer? We did and we are already planning to test them out with our new shields. Our engineering team is hard at work to provide you a custom bare bones boards to get your next gadget going.

Monday, May 27, 2019

This summer 2019. We can hardly wait! Just think of all the possibilities this small, lightweight microcontroller can do. 

New Arduino Nano 33 IoT
1. Secure WiFi and Bluetooth connectivity with a 6-axis IMU.
2. Pre-certified module with external processor ensures maintaining RF compliance when writing application code versus ESP32 modules where modifying code impacts certification.
3. On-board DC-DC power supply enables the board to be powered up to 21V maintaining high efficiency and offering a lot of current to external devices without overheating. This is a big improvement over other products on the market that have LDO and heat up quite a bit when powered at high voltages.

The Nano 33 IoT is essentially a MKR WiFi 1010, but sacrifices a battery charger and shield compatibility in favor of a miniaturized footprint and lower cost. The Nano 33 IoT is built around the ESP32, which is primarily aimed at WiFi but supports Bluetooth as well, although with higher power consumption than the Nano 33 BLE.

Sunday, May 26, 2019

Matlab on iPhone & iPad Devices

Do you want to use your iPhone or iPad to collect data from built in sensors such as acceleration, angular velocity, orientation, magnetic field, and GPS?

In this blog I will explain how to use MATLAB to collect data and log it.

First you will need access to MATLAB. Next, download the Mobile MATLAB app via Apple Store. From your lab top you will need to download the add-on 'MATLAB Support Package for Apple iOS Sensors'. 

Once all downloads have been made, open the mobile app and press the icon at the bottom right labeled 'More'. There you will see the Sensors option. Press it. This opens the menu for five (5) different built-in sensors. To begin, turn on one or more sensors. After the selection has been made, you can stream to MATLAB or log the data. 

Next, press the start button to collect data from your iOS device. *Before getting started you can change the frequency. If you chose to log the data, access the new file by pressing the icon to the right of the start button. See screenshots below.

Below is the link to the shared folder for reference. Use it as you please and please follow this blog.
Shared Folder - My iOS MobileSensorData

Look for more tech blogs like this. Simulink on Apple iOS Devices. Feel free to email me for questions.

Sunday, April 21, 2019


Today's blog is about the 74ls85 TTL. To build a circuit with this chip you will need two 4 pack dip switches and three led's. A datasheet is below. This TTL will compare the combined value for the 4-bit input of A inputs vs the B 4-bit inputs. The output will send a high to only one of the led's, AB depending on the condition. 

Comparison of words greater than 4-bit can be accomplished by cascading 'ls85 as described in the data sheet. The 74ls85 compares two separate 4-bit words, or numbers, coming from two different sources, such as counter, shift register, etc., including hard-wiring one number on the chip. One 4-bit word is placed on the inputs A0 thru A3, with the Least Significant Bit on A0. The other word is placed on inputs B0 thru B3 A 7 segment display can be implemented in the circuit by joining the inputs to a decoder that leads to the display. This will show numeric values.

555 Timer - LED Flasher with conductive 3D Filament - Astable Mode

June 23rd 2021 By Bits4Bots    Rapid circuit prototype with a 3D printer and conductive filament. This project features a simple circuit d...