Hi there everyone,
This is the first in hopefully a long and progressively more and more interesting series of modular projects.
Project Outline: Build a small, low power modular robotics platform
Stage 1 (Complete): Built the base. It's a 15cm diameter circle(ish) of plywood, with gearmotors, held in place with lego, for easy prototyping. Lego geartrain and wheels. Photos coming soon.
Stage 2 (More recently Complete): The weighty electronics. Namely, DC motor drivers and a 5v power regulation and distribution unit.
Based on a modified version of the circuit in David Cook's Intermediate Robot Building, this is a 6 MOSFET motor driver, driven by three Maxim 4427s (V. Grateful to Maxim for kindly giving me some free samples). Two of them (and four of the MOSFETS) make up standard common-gate H-Bridges. The other two n-ch MOSFETs lie between the sources of the H-Bridges and gnd, allowing me to brake, coast, fwd and rev two motors using a 6 pin header (Headers kindly supplied free by Molex). Pinout: M1 Fwd, M1 Rev, M1 Enable, M2 Enable, M2 Fwd, M2 Rev.
The circuit was built in a freeform/dead bug prototyping. The MOSFETS were glued+soldered together, back to back, making the entire thing much easier to assemble. This is the first time I had ever attempted a circuit of this complexity dead bug style, and I was delighted when it worked almost straight off, with few modifications! For a 16 year old who had tried similar things four years ago to no success, it was fantastic. Good soldering practise too I got to use my new soldering pencil for the first time, as well as experience mixing TH LEDs and SMD resistors.
Also on this board is a L7805 regulator, with a mixture of TH all. electroltyic caps and SMD tantalum. Nothing special, not even any reverse battery protection. I'm relying on the one-way-insertion KK header to protect my circuits.
Photos are attached, for anyone who wants to see just how messy my soldering is!
Next Up: Connecting some brains, in the form of a PIC (haven't decided what type yet), and making the platform move around a bit. After that: Active Reflective IR Obstacle Detection system.
Thanks for your help, More to come,
Barnaby
This is the first in hopefully a long and progressively more and more interesting series of modular projects.
Project Outline: Build a small, low power modular robotics platform
Stage 1 (Complete): Built the base. It's a 15cm diameter circle(ish) of plywood, with gearmotors, held in place with lego, for easy prototyping. Lego geartrain and wheels. Photos coming soon.
Stage 2 (More recently Complete): The weighty electronics. Namely, DC motor drivers and a 5v power regulation and distribution unit.
Based on a modified version of the circuit in David Cook's Intermediate Robot Building, this is a 6 MOSFET motor driver, driven by three Maxim 4427s (V. Grateful to Maxim for kindly giving me some free samples). Two of them (and four of the MOSFETS) make up standard common-gate H-Bridges. The other two n-ch MOSFETs lie between the sources of the H-Bridges and gnd, allowing me to brake, coast, fwd and rev two motors using a 6 pin header (Headers kindly supplied free by Molex). Pinout: M1 Fwd, M1 Rev, M1 Enable, M2 Enable, M2 Fwd, M2 Rev.
The circuit was built in a freeform/dead bug prototyping. The MOSFETS were glued+soldered together, back to back, making the entire thing much easier to assemble. This is the first time I had ever attempted a circuit of this complexity dead bug style, and I was delighted when it worked almost straight off, with few modifications! For a 16 year old who had tried similar things four years ago to no success, it was fantastic. Good soldering practise too I got to use my new soldering pencil for the first time, as well as experience mixing TH LEDs and SMD resistors.
Also on this board is a L7805 regulator, with a mixture of TH all. electroltyic caps and SMD tantalum. Nothing special, not even any reverse battery protection. I'm relying on the one-way-insertion KK header to protect my circuits.
Photos are attached, for anyone who wants to see just how messy my soldering is!
Next Up: Connecting some brains, in the form of a PIC (haven't decided what type yet), and making the platform move around a bit. After that: Active Reflective IR Obstacle Detection system.
Thanks for your help, More to come,
Barnaby
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