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Motor Sensor
Written by Administrator   
Wednesday, 11 May 2011 00:00

I’m working on a new stepper motor controller sensor for the Camera Axe. As you cans see I’ve decided to go for a really full featured stepper controller and put controls for 3 stepper motors and a microcontroller on the sensor. The camera axe will talk to this board via the IC2 protocol. This was the best way I could figure out to control more than 2 stepper motors with the camera axe, and even if you only need two stepper motors (three is really nice for some uses cases) this design has advantages. Some of those are being able to power off the stepper motors to save power, and using less program space/cpu cycles in the Camera Axe’s main controller. The only disadvantage is a slightly more expensive sensor board.

There are a lot of use cases such as:

  • Panoramic and/or rail timelapse
  • Gigapixel images
  • Interfacing with a microscope to do focus stacking and micro-gigapixel type images
  • Focus stacking and gigapixel type images for macro images
  • Lots more

The biggest unknown I have about this board is if I really need a separate 5V power source instead of taking it from the batteries powering the motors. I have some experience of this sort of setup (same power source) working fine, but I have read that sometimes it can lead to flakiness. I wonder if that’s true or if people didn’t put enough filter caps in their design.

If anyone wants to help with the mechanical designs for some of these use cases let me know.

Comments are about the design or the use cases are always welcome.

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Last Updated on Wednesday, 11 May 2011 01:16
PIC16F628 intelligent battery charger
Written by Administrator   
Wednesday, 20 April 2011 00:00

This project is an intelligent battery charger based on PIC16F628.

PIC16F628 intelligent battery charger-[Link]


Last Updated on Wednesday, 20 April 2011 22:51
Float Charging NiMH Cells
Written by admin   
Tuesday, 22 March 2011 00:00

Authors: admin

Graham explores a popular method for charging NiMH cells – float charging.

Float charging has the advantage of keeping the cells fully charged and ready to use without the potential damage of long-term trickle charging or the cost of low-discharge cells. This approach works because NiMH cells do not have the memory problems associated with Nicads.

Float Charging NiMH Cells - 


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Last Updated on Tuesday, 22 March 2011 01:33
Ammeter and Precision Rectifier
Written by delabs   
Friday, 18 March 2011 00:00
Studying current measurement is a prerequisite for many of the measuring techniques. The current parameter mainly specifies the power consumption in a circuit, given the value of resistance. It is found convenient to measure current rather than voltage for knowing power output and determining efficiency. It may be required to measure leakages in circuits at certain times. Hence the measurement of current constitutes a priority.

Ammeter and Precision Rectifier

Measurement of DC Current -

The circuit diagram for the measurement of current (d.c. and a.c. modes) is shown aside. For measurement of current switch SI is operated. The switch S-ad is kept in d.c. mode. This enables the current to pass through a shunt circuit consisting of resistors R26, R27, R28, R29 and R 30. The current ranges are provided in 5 decades i.e. 200 micro-amps, 2 milli-amps, 20 milli-amps, 200 milli-amps and 2 amps. An additional current range that can be read upto 20 Amps is also provided. However, for measuring this high current the green terminal provided on the meter should be used. When a current to be measured is fed to the input terminals of the instrument appropriately, a voltage proportional to the current through the shunt resistor is fed into the DPM which measures the d.c. voltage which in turn indicates the d.c. current being fed.

Measurement of AC Current -

In case of a.c. measurement, the switch S-ad is kept in a.c. mode. The a.c. current path is similar to the d.c. current path in the shunt resistor. However the voltage tapped across the shunt resistor is fed into IC2 which is a buffer. The output of IC2 is fed to IC3 through capacitors C10 and C11. This IC is an operational amplifier acting as a precision rectifier. The output of IC3 is fed to the input of the DPM for measuring the a.c. current being fed to the input terminals. It can be seen that the current measurement is similar to the voltage measurement except that the attenuator chain is replaced by the shunt resistor circuit.

(This is scanned-ocr from my earlier file, some mistakes corrected - delabs)

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Last Updated on Friday, 18 March 2011 00:34
Expanded Scale Battery Volt Meter
Written by Administrator   
Friday, 11 March 2011 00:00

This circuit is used to measure the voltage on a 12V (nominal) lead acid rechargeable battery system. It was specifically designed for use in solar powered systems, but is general enough that it can be used for automotive or other 12V systems. Lead acid batteries normally spend their working lifetime in the voltage range of 11-15 Volts. This meter circuit was designed to show the voltage range of 10-15V on an analog meter movement, it can be used to show the battery charge state from empty to full.


Last Updated on Friday, 11 March 2011 02:39
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