Motorized 5" Telescope
Stepper Motor Circuit Boards
The electric circuit board for controlling stepper motors came out after figuring out all the specifications of the components. Some sketches were necessary to done. Then Auto-Cad was a great tool for drawing the wires and locate the components. Mainly my circuit is similar than shown in Mel's page. I didn't use opto-isolators and couldn't find TIP120 from a local electric dealer, so I used TIP122 transistors. I also placed the small hand-pad diodes on the board instead of installing them inside of the hand-pad. After soldering work and changing the InverterOutPut (!) to 1 the board started to work.
IR Hand-Pad
The newest idea was to convert the hand-pad to IR-operated. I found out a couple of I found out a couple of web pages which describe the use of Holtek's encoder HT12A and decoder HT12D in transmitter and receiving circuits. The circuits were pretty simple and I drawed them by using Autocad. After plotting I cut the paper image from the wire side to match the board size and fixed it on the copper surface with a few drops of glue. Then I used a sharp, small nail and hammer to mark the pin holes. Drilling with 1 mm drill, cleaning the surface and wires were drawn with free hand using Textmark 500 pen (have heard that SANFORD Sharpie pen would also be good). Well, I have seen better and nicer boards than mine but to produce only a couple of boards the method is good enough.
A few words of the circuits. I try to keep my stories short. The main idea is to activate parallel port's pins nro 10...13 with different combinations as described in Mel's pages. Normally this is handled by leading +5V through push button of hand-pad to one or more pins of parallel port. The same principle is used with IR- system. I used HT12A transmitter IC which works so that if pins 10...13 of IC are pulled to ground the receiver HT12D's similar pins will then latch at 0V. If no buttons of transmitter is pressed no pins of parallel port is activated. Pins 3...8 of HT12A are for setting the unique signal. I left them all open and important is just to set the same pins of receiver with identical settings. Otherwise the receiver will not decode the signal.
The electric circuit board for controlling stepper motors came out after figuring out all the specifications of the components. Some sketches were necessary to done. Then Auto-Cad was a great tool for drawing the wires and locate the components. Mainly my circuit is similar than shown in Mel's page. I didn't use opto-isolators and couldn't find TIP120 from a local electric dealer, so I used TIP122 transistors. I also placed the small hand-pad diodes on the board instead of installing them inside of the hand-pad. After soldering work and changing the InverterOutPut (!) to 1 the board started to work.
IR Hand-Pad
The newest idea was to convert the hand-pad to IR-operated. I found out a couple of I found out a couple of web pages which describe the use of Holtek's encoder HT12A and decoder HT12D in transmitter and receiving circuits. The circuits were pretty simple and I drawed them by using Autocad. After plotting I cut the paper image from the wire side to match the board size and fixed it on the copper surface with a few drops of glue. Then I used a sharp, small nail and hammer to mark the pin holes. Drilling with 1 mm drill, cleaning the surface and wires were drawn with free hand using Textmark 500 pen (have heard that SANFORD Sharpie pen would also be good). Well, I have seen better and nicer boards than mine but to produce only a couple of boards the method is good enough.
A few words of the circuits. I try to keep my stories short. The main idea is to activate parallel port's pins nro 10...13 with different combinations as described in Mel's pages. Normally this is handled by leading +5V through push button of hand-pad to one or more pins of parallel port. The same principle is used with IR- system. I used HT12A transmitter IC which works so that if pins 10...13 of IC are pulled to ground the receiver HT12D's similar pins will then latch at 0V. If no buttons of transmitter is pressed no pins of parallel port is activated. Pins 3...8 of HT12A are for setting the unique signal. I left them all open and important is just to set the same pins of receiver with identical settings. Otherwise the receiver will not decode the signal.
Each pins 10...13 of HT12A can be pulled to ground or what ever combinations of them so the solution is clear. I decided that the pin number 13 of HT12A equals to the pin number 13 of the parallel port, pin 12 to 12 and so.
For example to rotate telescope's azimuth shaft to anti-clockwise the pin 10 of the parallel port has to be pulled to logic 1 and clockwise the pins 13 and 12. When the transmitter's ccw-button is pressed down the HT12A sends a signal, HT12D decodes it and the pin 10 will go to 0V. Then the base of the BC557A (PNP) is 0V and the current can go from emitter to collector and via 220 ohm resistor to the 4N26 optocoupler. Detector part of 4N26 will turn on letting the +5V (stepper circuit's regulated voltage) to go to pin 10 of the parallel port.
There are a few mistakes on the drawings of PC boards circuits: The correct rates for the capacitors next to the 455 kHz resonator on the transmitter circuit should be 0.1 pF instead of 0,1 uF. Only six diodes (BAV103) is enough on the transmitter circuit instead of ten. Also the circuits can be made smaller and these are just one way to make the circuits.
In practice it seems that sensor (in my case TSOP1740) will catch the signal about from 5 to 6 meters away and from 180 degrees wide area. I think that is enough because most of the time I am next to the telescope looking through the eyepiece. Later I will see how long the lithium battery CR2032 of the transmitter in use will last (rated 220 mAh). Anyway, if no buttons are pressed HT12 A should use only a few micro amps. Because of the regulator 7805 the receiver will use a few mA, so the circuit is good to furnish with a main power switch to save 9V battery while the system is not in use.
The IR hand-pad's (left on the photo, right the serial UIR) dimensions are in my case 120x70x20 mm. It is little bit more than my wire-pad's size. I thought that it would be too hard trying to install the buttons on the electric board and drill exactly seven button holes to the cover of the case. So, I happened to find small board push-buttons (button part round, D4 mm) which frame is square app. 10x10 mm. I drilled the 6 mm holes to the cover of the case and fixed the buttons to the lower surface of the cover by using a few tiny little drops quick-glue. (!) So, the wires go from the board to each button and back. Because of the small thickness of the push-buttons the case thickness is that reasonable 20 mm. Well, the IR remote hand-pad is far from a nice TV remote controller but gloves in your hand you can push the buttons quit well. :)
A couple of points of using IR hand-pad with Scope-program is good to notify. If you push any of the hand-pad's button down and give an order to Scope to turn the telescope. Then you turn (keeping the button down) the transmitter away from the sensor's sensing area the led on the receiver circuit switches off indicating no signal. If you now release the pushed button the telescope keeps doing given order!!! Well, re-pointing the transmitter to the sensor and short push to any of the buttons of coarse release the action. Theoretically it would be possible that if the lithium battery of transmitter would be near end of it's life and am. situation occurs the telescope would be difficult to stop. In this case turning the power off from the receiver would safe the situation.
IR Control of Scope-Program
After building the IR-hand-pad I started to wonder should it be possible to control the Scope.exe program remotely. Because my hobby time is limited and I am not an electronic specialist it took rather long time before I managed to figure out how it goes. Anyway, from the pages Universal Infrared Receiver by Ties Boss found the answer. On the download page can be found DOS TSR program that simulates keyboard (by R.vd.Geest). I build a PIC16F84 version by using PIC16F84A micro controller and it seems to function properly with Scope.exe. Why to use Scope.exe remotely? Well, in my case I am forced to locate the laptop in the heated weather cover in winter times and putting hands every time inside the cover is too cold for my fingers and it is also frustrating. In the future I may build a garage and the rear end of it a ware room for the garden stuff. That way there would open also a possibility to use the ware part of the garage as a poor man's observatory by locating the laptop inside the ware room and controlling the scope.exe remotely with UIR and TV remote controller... Well, right now I will try to use my house cellar for a warm place for the laptop. The laptop's screen will face outwards through the cellar's window while the telescope is located outside a few meters from the window. This way there would be as less as possible telescope parts to carry out in the observing night and no fear of a frozen laptop. Just the telescope with battery out, the parallel port cable plug to the wall socket, power on to the laptop (while starting it starts the scope.exe too) and you would be on your way to observing... Sounds pretty easy. Well, you have to try to make your actions with telescope as comportable and easy as you can especially over here in north.
It seems that almost every functions can be controlled by for example TV remote controller. It requires app. 16...20 buttons to be programmed to control Scope.exe normally. Of coarse it depends on the user. Mel's the latest Scope.exe versions (starting from 2002-Jan-15) allow now up/down cursor control to data file selection boxes. Earlier you should have had a rather large ir-controller covering all the letters starting from A. So, now all the functions of Scope.exe controlled by UIR is practically possible. Great!
Finally, the UIR uses the laptop's serial port so in many cases it might be reserved for other purposes.
Setting up the Scope.exe
At the beginning I was confused how to set up the scope.exe. Different motors acted different ways. I think the best way is to try different values after reading what Mel has written on his pages. I have also came a conclusion that it would be good to choose stepper motors (unipolar, permanent magnet) which you can drive 2x or 3x over voltage. For example my motors are rated 4 V / 1,1 A and I drive them 12 VDC. Also flywheels seem to give their extra boost for the max. slewing speeds. I think there is no need here to try to give parameters for the scope.exe's config.dat file because there are good web-pages available which describe the setting up progress.
For example to rotate telescope's azimuth shaft to anti-clockwise the pin 10 of the parallel port has to be pulled to logic 1 and clockwise the pins 13 and 12. When the transmitter's ccw-button is pressed down the HT12A sends a signal, HT12D decodes it and the pin 10 will go to 0V. Then the base of the BC557A (PNP) is 0V and the current can go from emitter to collector and via 220 ohm resistor to the 4N26 optocoupler. Detector part of 4N26 will turn on letting the +5V (stepper circuit's regulated voltage) to go to pin 10 of the parallel port.
There are a few mistakes on the drawings of PC boards circuits: The correct rates for the capacitors next to the 455 kHz resonator on the transmitter circuit should be 0.1 pF instead of 0,1 uF. Only six diodes (BAV103) is enough on the transmitter circuit instead of ten. Also the circuits can be made smaller and these are just one way to make the circuits.
In practice it seems that sensor (in my case TSOP1740) will catch the signal about from 5 to 6 meters away and from 180 degrees wide area. I think that is enough because most of the time I am next to the telescope looking through the eyepiece. Later I will see how long the lithium battery CR2032 of the transmitter in use will last (rated 220 mAh). Anyway, if no buttons are pressed HT12 A should use only a few micro amps. Because of the regulator 7805 the receiver will use a few mA, so the circuit is good to furnish with a main power switch to save 9V battery while the system is not in use.
The IR hand-pad's (left on the photo, right the serial UIR) dimensions are in my case 120x70x20 mm. It is little bit more than my wire-pad's size. I thought that it would be too hard trying to install the buttons on the electric board and drill exactly seven button holes to the cover of the case. So, I happened to find small board push-buttons (button part round, D4 mm) which frame is square app. 10x10 mm. I drilled the 6 mm holes to the cover of the case and fixed the buttons to the lower surface of the cover by using a few tiny little drops quick-glue. (!) So, the wires go from the board to each button and back. Because of the small thickness of the push-buttons the case thickness is that reasonable 20 mm. Well, the IR remote hand-pad is far from a nice TV remote controller but gloves in your hand you can push the buttons quit well. :)
A couple of points of using IR hand-pad with Scope-program is good to notify. If you push any of the hand-pad's button down and give an order to Scope to turn the telescope. Then you turn (keeping the button down) the transmitter away from the sensor's sensing area the led on the receiver circuit switches off indicating no signal. If you now release the pushed button the telescope keeps doing given order!!! Well, re-pointing the transmitter to the sensor and short push to any of the buttons of coarse release the action. Theoretically it would be possible that if the lithium battery of transmitter would be near end of it's life and am. situation occurs the telescope would be difficult to stop. In this case turning the power off from the receiver would safe the situation.
IR Control of Scope-Program
After building the IR-hand-pad I started to wonder should it be possible to control the Scope.exe program remotely. Because my hobby time is limited and I am not an electronic specialist it took rather long time before I managed to figure out how it goes. Anyway, from the pages Universal Infrared Receiver by Ties Boss found the answer. On the download page can be found DOS TSR program that simulates keyboard (by R.vd.Geest). I build a PIC16F84 version by using PIC16F84A micro controller and it seems to function properly with Scope.exe. Why to use Scope.exe remotely? Well, in my case I am forced to locate the laptop in the heated weather cover in winter times and putting hands every time inside the cover is too cold for my fingers and it is also frustrating. In the future I may build a garage and the rear end of it a ware room for the garden stuff. That way there would open also a possibility to use the ware part of the garage as a poor man's observatory by locating the laptop inside the ware room and controlling the scope.exe remotely with UIR and TV remote controller... Well, right now I will try to use my house cellar for a warm place for the laptop. The laptop's screen will face outwards through the cellar's window while the telescope is located outside a few meters from the window. This way there would be as less as possible telescope parts to carry out in the observing night and no fear of a frozen laptop. Just the telescope with battery out, the parallel port cable plug to the wall socket, power on to the laptop (while starting it starts the scope.exe too) and you would be on your way to observing... Sounds pretty easy. Well, you have to try to make your actions with telescope as comportable and easy as you can especially over here in north.
It seems that almost every functions can be controlled by for example TV remote controller. It requires app. 16...20 buttons to be programmed to control Scope.exe normally. Of coarse it depends on the user. Mel's the latest Scope.exe versions (starting from 2002-Jan-15) allow now up/down cursor control to data file selection boxes. Earlier you should have had a rather large ir-controller covering all the letters starting from A. So, now all the functions of Scope.exe controlled by UIR is practically possible. Great!
Finally, the UIR uses the laptop's serial port so in many cases it might be reserved for other purposes.
Setting up the Scope.exe
At the beginning I was confused how to set up the scope.exe. Different motors acted different ways. I think the best way is to try different values after reading what Mel has written on his pages. I have also came a conclusion that it would be good to choose stepper motors (unipolar, permanent magnet) which you can drive 2x or 3x over voltage. For example my motors are rated 4 V / 1,1 A and I drive them 12 VDC. Also flywheels seem to give their extra boost for the max. slewing speeds. I think there is no need here to try to give parameters for the scope.exe's config.dat file because there are good web-pages available which describe the setting up progress.
Copyright©2008 Aki Lötjönen
