Weer een laser projectje van mij. Een dubbele LAB laser driver. Ontworpen en voor 90% afgebouwed in 2 dagen, en de rest vandaag. Ik maak gebruik van de precisie spanning-naar-stroom converters die ik eerder al heb gebruikt als laser driver, maar dan geoptimaliseerd voor low drop-out.
(de rest is in engels omdat ik het net ook op laserpointerforums heb gepost)
It is designed with the following features:
- On/off switch
- Safety key switch with 8 seconds delay between safety switch turn on and laser power on. Laser power is physically inhibited by a relay. Output is also inhibited when the key is already turned on when turning main power on. (intelligence in microcontroller)
- Channel 1: 1-4V output, max current programmable between 250 and 500mA (red laser diodes)
- Channel 2: 4-7V output, max current programmable between 140 and 310mA (violet laser diodes)
- Each channel has a power adjust pot
- Each channel has a burst button which maxes out the supplied current when pressed.
- Each channel has an emission indicator with programmable threshold. They're a different color than any possible laser colors, as it should be visible through safety goggles.
- Each channel has an external safety interlock switch (which inhibits laser power when disconnected).
- Each channel has an external analog modulation input which overrules the internal pot automatically.
- Each channel has an on-time recorder v2 (big version), which can be read out using an external plug.
- One of the two channels can be switched off or both are enabled. (small 3-way switch between the two potmeters)
- Laser modules are connected using a common BNC connector. Each laser module must have it's own surge protection inside because of this.
(all images are clickable)
PCB Schematic (external components not shown, only connection points):
Work in progress:
This was an optional module from a Philips video recorder from 1984. It's use is unknown.
Harvested PCB with corner cut out and my own PCB mounted in it's place.
Plugs from top to bottom:
- Driver 1 output
- Driver 2 output
- Driver 1 interlock and modulation input
- Driver 2 interlock and modulation input
- Digital readouts for both on-time recorders.
The case I use is so ultra tight, I had to move some parts around on the PCB because front panel objects were in the way. Here are some photos showing how tight it is. Watch the switch poke upward while the caps (yellow blobs) poke downward.
Potmeter in lower front and heat sink from a voltage regulator in the center
The plug at the left is a dummy safety interlock switch
No, it's not upside down, I just need to make a good front panel layout
One recorder installed here on the lower right