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Need some help with a circuit

Need some help with a circuit

Postby 01i » Mon Nov 08, 2010 10:48 pm


I am intending to create an automated scanner using a hacked robot arm ( ... robot-arm/)

I intend to modify the system slightly, so that I can improve the wrist motor into a 0.9 degree stepper (Nanotec ST4209S1006-B) and for the turntable an 18 degree stepper (SP1518M0204-A)

Adding the steppers means I'll need an extra H-Bridge (Texas Instruments SN754410NEG4) from the Larry circuit, and - I assume - a shift controller (Texas Instruments CD74HC595M)

I may include an LCD display eventually

I've made up a basic diagram of how I think the circuit ought to look, however I dont know enough about controlling power levels with resisters etc.

Could somebody help out by letting me know what I need to add to the circuit, or point me to an online circuit testing tool that I can design it with

Once complete I'll post design info, pics and code in here

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Joined: Tue Nov 02, 2010 11:25 pm

Re: Need some help with a circuit

Postby JD_Mortal » Tue Nov 09, 2010 3:32 am

Well, resistors are not good for controlling power-levels, unless that is a last resort. (Higher resistance causes more heat, causes more resistance, causes failure, under any steady load.)

There are shields you can use, since you have an arduino.

I suggest this driver-board... You would need 2 for your diagram layout, 2 stepper, 4 DC (Note, this is for smaller load servo's, <1.2A, can be modded for higher amps.) ... duino.html

• 2 connections for 5V 'hobby' servos with high-resolution dedicated timer - no jitter
• 4 H-Bridges: L293D chipset provides 0.6A per bridge (1.2A peak)
• Thermal shutdown protection, internal kickback protection diodes.
• Can run motors on 4.5VDC to 36VDC (separate power supply)
• Up to 4 bi-directional DC motors with individual 8-bit speed selection (~0.5% resolution)
• Up to 2 stepper motors (unipolar or bipolar) with single coil, double coil or interleaved stepping.
• Pull down resistors keeps motors disabled during power-up
• Big terminal block connectors to easily hook up wires (10-22AWG) and power
• Arduino reset button brought up top (Diecimila/Duemilanove only)
• 2-pin terminal block and jumper to connect external power, for separate logic/motor supplies
DIY laser-line, Hand sweep scanning, Generic driverless webcam (640x480), Cardboard background rig, Adequate results.
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