Hello group,
Totally new to the forum, and have limited electronics & laser competence; thanks in advance for reading this thread!
I'm an amateur astronomer, and wish to modify a cheap green laser pointer to help orient my telescope more conveniently.
The mods involve:
The specs for the pointer I obtained here are:
![laser pointer 2.jpg laser pointer 2.jpg](https://laserpointerforums.com/data/attachments/45/45817-2e4c5ca4017c1100355c26b1d4ae1e6c.jpg?hash=LkxcpAF8EQ)
![laser pointer 1.jpg laser pointer 1.jpg](https://laserpointerforums.com/data/attachments/45/45818-0a115a705b9616161b6bf036f3571f89.jpg?hash=ChFacFuWFh)
Here is my first stab at a circuit to accomplish what I want.
It basically consists of:
![schematic.jpg schematic.jpg](https://laserpointerforums.com/data/attachments/45/45819-eef168304dc605b95decb253fd1b6ae1.jpg?hash=7vFoME3GBb)
So far, this doesn't work![Confused :confused: :confused:](https://cdn.jsdelivr.net/joypixels/assets/8.0/png/unicode/64/1f615.png)
I retested the laser by itself, and it works fine.
The voltage across the laser leads is 2 volts, and varies only slightly when I turn the trim pot screw.
When I replace the laser module by a LED, the circuit does work as expected.
So, where am I going wrong? Something tells me I'm not setting the transistor up properly.
Any suggestions to go about it any better way?
Thanks a million in advance!
Ron
Montreal
Totally new to the forum, and have limited electronics & laser competence; thanks in advance for reading this thread!
I'm an amateur astronomer, and wish to modify a cheap green laser pointer to help orient my telescope more conveniently.
The mods involve:
- removing button
- removing batteries
- powering from a circuit on which the button is mounted
The specs for the pointer I obtained here are:
- Wavelength: 532nm
- Visible Color: Green
- Body Material: Aviation Aluminum
- Powered by: AAA*2 (batteries not included)
- Activation: Pushbutton
- Light distance: Over 500 meters
- Spot size: Minimum Spot Diameter ≤φ1.0mm; Spot Diameter at 15m <Φ18mm
- Operating Voltage: DC = 3.0V
- Power: 5mw
- Size: 17cm x 1.5cm (length x body diameter)
- Weight: 50g
![laser pointer 2.jpg laser pointer 2.jpg](https://laserpointerforums.com/data/attachments/45/45817-2e4c5ca4017c1100355c26b1d4ae1e6c.jpg?hash=LkxcpAF8EQ)
![laser pointer 1.jpg laser pointer 1.jpg](https://laserpointerforums.com/data/attachments/45/45818-0a115a705b9616161b6bf036f3571f89.jpg?hash=ChFacFuWFh)
Here is my first stab at a circuit to accomplish what I want.
It basically consists of:
- a LM317 to step voltage from 5.5V to 4.0V;
- a 2N2222A (npn) transistor to switch on or off using a SPST (or eventually an Arduino digital IO pin)
- the laser module itself, with its control circuit as in the thumbnails above;
- a trim pot (in test) to limit current;
![schematic.jpg schematic.jpg](https://laserpointerforums.com/data/attachments/45/45819-eef168304dc605b95decb253fd1b6ae1.jpg?hash=7vFoME3GBb)
So far, this doesn't work
![Confused :confused: :confused:](https://cdn.jsdelivr.net/joypixels/assets/8.0/png/unicode/64/1f615.png)
I retested the laser by itself, and it works fine.
The voltage across the laser leads is 2 volts, and varies only slightly when I turn the trim pot screw.
When I replace the laser module by a LED, the circuit does work as expected.
So, where am I going wrong? Something tells me I'm not setting the transistor up properly.
Any suggestions to go about it any better way?
Thanks a million in advance!
Ron
Montreal
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