PICcontroller
It was discovered through experience why the 6V EQ-5 hand controller should not be connected to 12V by mistake. It only took about half a second to damage the hand controller. Upon inspection, it became clear that the large 40-pin microcontroller, which serves as the "brains" of the handset, was destroyed. Further examination revealed that the controller lacks overvoltage and reverse voltage protection. The microcontroller is quite susceptible to damage. A search for replacement hand controllers or the programmed microcontroller yielded no results; one must purchase the entire unit at full price, including the hand controller and stepper motors. However, there is an alternative: building a custom hand controller with overvoltage protection, unlike the standard Chinese model. This requires learning to program a microcontroller from scratch, as using a 555 timer circuit is not viable due to its insufficient stability. A PIC microcontroller operating on a 4MHz crystal is expected to provide adequate accuracy. The hand controller design is adaptable in terms of project boxes and switches, with a total cost estimated between £20 and £30, depending on part sources. Additionally, a PIC programmer is necessary, such as the Velleman K8048 kit, which is a budget-friendly option but requires assembly. Alternatively, pre-programmed PICs can be purchased for £7.00 each, including postage. The design allows for adjustable slew speed, faster than standard controllers, and the source code is available for modifications. Slew buttons for each direction and a stop button for the RA drive are included, along with switches to reverse the slew directions for both DEC and RA axes. This feature is beneficial for switching between eyepiece and webcam imaging. The RA direction switch does not affect the RA drive direction. The design employs two PICs, one for RA drive and one for DEC drive, to maintain accurate timing for the RA drive, as running DEC code on the same chip could disrupt timing. The DEC circuit omits the crystal oscillator, utilizing the PIC's internal 4MHz oscillator instead. The basic circuit includes the PIC microcontroller and an L293D H-bridge driver, requiring very few additional components for functionality.
The custom-built hand controller offers a significant advantage over the standard model by incorporating protective features that prevent damage from overvoltage and reverse polarity. The design utilizes a dual-PIC architecture, which allows for dedicated timing control for both the Right Ascension (RA) and Declination (DEC) axes, ensuring precise movement control essential for astronomical applications. The use of an L293D H-bridge driver facilitates the control of stepper motors, enabling smooth and reliable operation.
The microcontroller programming aspect is crucial and entails writing firmware that can handle user inputs from the slew buttons and switches effectively. The firmware should manage the timing of the motor drive signals, ensuring that they are synchronized with the desired slew speed. The slew speed can be adjusted via software, allowing for flexibility based on user preferences or specific observational needs.
In addition to the basic functionality, the controller's design includes user-friendly features such as direction swapping switches, which enhance usability during different operational modes (e.g., switching from visual observation to imaging). This adaptability is particularly valuable in dynamic observational environments where quick adjustments are necessary.
To summarize, this custom hand controller design not only addresses the inherent vulnerabilities of commercially available models but also empowers users with the ability to tailor their equipment to their specific needs. The combination of robust hardware design, precise microcontroller programming, and user-focused features positions this project as an excellent solution for amateur astronomers seeking reliability and customization in their astronomical instruments.found out the hard way why the 6v EQ-5 hand controller should not be connected to 12v by accident. It only took, literally half a second to kill my hand controller. After some examination it became obvious that I had destroyed the large 40 pin micro controller, the "brains" of the handset. Upon further examination it became obvious that the controller has no form of either, overvoltage protection
or reverse voltage protection. It doesn`t take much to kill that chip. So I thought, surely if the hand controller is that easy to destroy, a simple Google search would reveal a source of either replacement hand controllers or even better (thinking of the environment) just the programmed micro controller. It turns out that you have to buy the lot, at full price. The hand controller and steppers, everything! Well, I thought. there must be another way! And I am happy to say there is. Build your own hand controller. I could even protect it from over voltage, unlike the poxy standard chinese hand controller. The only down side was I had to learn to program a micro controller from scratch. Using a 555 timer circuit wasn`t an option because the stability of the 555 isn`t accurate enough. However a PIC micro controller running off a 4MHz crystal ought to be quite accurate. The image opposite is the hand controller I came up with. The project box and switches etcyou choose use are entirely up to you. I chose these because they are what I had to hand. The total cost to build the unit will be between £20 and £30 depending on where you source the parts.
Over and above that, if you don`t already have one you will need an PIC programmer. I used the Velleman K8048 kit. This was a relatively cheap option but you have to build it yourself. Take a look at, the kit is available in the UK from and do a search for K8048. If you don`t want to get into PIC micro controller programming then I can supply the PIC`s at £7. 00 each fully programmed up. The price includes postage and packaging. Contact me at astro(dot)bloke(at)ntlworld(dot)com for more details. I have a pay pal account or I will accept a cheque. Alternatively you could get a friend to program you chip for free ifthey have a PIC programmer. You are able to select the slew speed. These are faster than the standard hand controller. The source code is available if you want to change this speed. If you ask nicely I might provide a second HEX file with a different slew rate for the switch positions. There are Slew buttons provided for each direction and also a stop button which will stop the RA drive.
I have also provided two switches to swap the directions of the slew buttons. One for DEC and one for RA. These are useful if, for example, you swap from using an eyepiece to webcam imaging, flick the switches and the buttons move the object in the direction you expect. It also allows you to use the controller either way up according to your preference. Please note that the RA direction switch does not affect the RA drive direction. I decided at the beginning to use two PIC`s. One for the RA drive and one for the DEC drive. The main reason for this was that the RA drive timing has to be accurate. If I have to start running DEC code on the same Chip as the RA drive, it would be very difficult to keep the timing right.
Over and above this, there simply aren`t enough in/out pins to go around on a PIC16F627. The RA drive circuit and the DEC drive circuit are essentially the same. However the DEC circuit omits the crystal oscillator. This is because timing isn`t critical for the DEC drive, I`ve used the PIC`s internal 4MHz oscillator instead. Note: that the internal oscillator of the PIC16F627A is also 4MHz. The basic circuit consists of the PIC micro controller and a L293D which is an H-bridge driver. There are very few extra components needed for the circuit to work. The stepp 🔗 External reference
The custom-built hand controller offers a significant advantage over the standard model by incorporating protective features that prevent damage from overvoltage and reverse polarity. The design utilizes a dual-PIC architecture, which allows for dedicated timing control for both the Right Ascension (RA) and Declination (DEC) axes, ensuring precise movement control essential for astronomical applications. The use of an L293D H-bridge driver facilitates the control of stepper motors, enabling smooth and reliable operation.
The microcontroller programming aspect is crucial and entails writing firmware that can handle user inputs from the slew buttons and switches effectively. The firmware should manage the timing of the motor drive signals, ensuring that they are synchronized with the desired slew speed. The slew speed can be adjusted via software, allowing for flexibility based on user preferences or specific observational needs.
In addition to the basic functionality, the controller's design includes user-friendly features such as direction swapping switches, which enhance usability during different operational modes (e.g., switching from visual observation to imaging). This adaptability is particularly valuable in dynamic observational environments where quick adjustments are necessary.
To summarize, this custom hand controller design not only addresses the inherent vulnerabilities of commercially available models but also empowers users with the ability to tailor their equipment to their specific needs. The combination of robust hardware design, precise microcontroller programming, and user-focused features positions this project as an excellent solution for amateur astronomers seeking reliability and customization in their astronomical instruments.found out the hard way why the 6v EQ-5 hand controller should not be connected to 12v by accident. It only took, literally half a second to kill my hand controller. After some examination it became obvious that I had destroyed the large 40 pin micro controller, the "brains" of the handset. Upon further examination it became obvious that the controller has no form of either, overvoltage protection
or reverse voltage protection. It doesn`t take much to kill that chip. So I thought, surely if the hand controller is that easy to destroy, a simple Google search would reveal a source of either replacement hand controllers or even better (thinking of the environment) just the programmed micro controller. It turns out that you have to buy the lot, at full price. The hand controller and steppers, everything! Well, I thought. there must be another way! And I am happy to say there is. Build your own hand controller. I could even protect it from over voltage, unlike the poxy standard chinese hand controller. The only down side was I had to learn to program a micro controller from scratch. Using a 555 timer circuit wasn`t an option because the stability of the 555 isn`t accurate enough. However a PIC micro controller running off a 4MHz crystal ought to be quite accurate. The image opposite is the hand controller I came up with. The project box and switches etcyou choose use are entirely up to you. I chose these because they are what I had to hand. The total cost to build the unit will be between £20 and £30 depending on where you source the parts.
Over and above that, if you don`t already have one you will need an PIC programmer. I used the Velleman K8048 kit. This was a relatively cheap option but you have to build it yourself. Take a look at, the kit is available in the UK from and do a search for K8048. If you don`t want to get into PIC micro controller programming then I can supply the PIC`s at £7. 00 each fully programmed up. The price includes postage and packaging. Contact me at astro(dot)bloke(at)ntlworld(dot)com for more details. I have a pay pal account or I will accept a cheque. Alternatively you could get a friend to program you chip for free ifthey have a PIC programmer. You are able to select the slew speed. These are faster than the standard hand controller. The source code is available if you want to change this speed. If you ask nicely I might provide a second HEX file with a different slew rate for the switch positions. There are Slew buttons provided for each direction and also a stop button which will stop the RA drive.
I have also provided two switches to swap the directions of the slew buttons. One for DEC and one for RA. These are useful if, for example, you swap from using an eyepiece to webcam imaging, flick the switches and the buttons move the object in the direction you expect. It also allows you to use the controller either way up according to your preference. Please note that the RA direction switch does not affect the RA drive direction. I decided at the beginning to use two PIC`s. One for the RA drive and one for the DEC drive. The main reason for this was that the RA drive timing has to be accurate. If I have to start running DEC code on the same Chip as the RA drive, it would be very difficult to keep the timing right.
Over and above this, there simply aren`t enough in/out pins to go around on a PIC16F627. The RA drive circuit and the DEC drive circuit are essentially the same. However the DEC circuit omits the crystal oscillator. This is because timing isn`t critical for the DEC drive, I`ve used the PIC`s internal 4MHz oscillator instead. Note: that the internal oscillator of the PIC16F627A is also 4MHz. The basic circuit consists of the PIC micro controller and a L293D which is an H-bridge driver. There are very few extra components needed for the circuit to work. The stepp 🔗 External reference