Laser diode driver ebay

The proposed schematic is able to sink constant currents from 0 mA up to 0. If higher currents are desired, small schematics changes are required mainly: change the value of one resistor. The main active part of the circuit is a single supply dual operational amplifier Opamp. One of the integrated opamps is used as buffer, the second one in voltage to current converter configuration. The schematics of the driver is presented on the picture.

A 5 V reference voltage is created by the Zenner diode D2 and the resistor R4. This voltage is filtered by the use of the capacitor C2 and applied to the input of the opamp connected as buffer. The buffer is loaded with trimmer potentiometer connected to ground. In this way on its middle terminal the voltage can vary between 0 and the reference voltage. The second opamp together with the power NMOS transistor work as voltage to current converter - the source voltage of the transistor is identical to the input voltage of the second opamp.

This voltage appears at the current defining resistor R5. I have used 5V Zenner diode and 10 Ohm R5 resistor - the maximum possible generated current is mA. If higher current is needed, either the reference voltage should be increased, either the value of R5 shall be reduced. Because high current can flow through the NMOS transistor, it must be enough strong to sustain it. The power generated by the R5 must be also properly dissipated.

In my case the maximum power generated by R5 is 2. I have used 5 W resistor. The resitor R3 is optional. In some cases R1 also. R2 and C1 are used to protect the laser diode from some voltage spikes. Some words about the used opamp and NMOS transistor: The power NMOS transistor normally has a big working area, what in most of the cases presumes big input capacitance. For some devices it can reach some dozens of nanofarades. This capacitance appears as capacitive load for the opamp.

The opamp must be able to drive such kind of big capacitive load, without losing its stability. Some opamps are compensated for similar loads, but a plenty of standard opamps will oscillate. You have carefully to check in both datasheets of the opamp and the NMOS , what is the gate capacitance of the power NMOS transistor, and is the opamp stable with this load.

In some cases, even the opamp is not stable with the specific NMOS transistor as load, the stability can be drastically improved by the "isolating" the load from the opamp output by the use of simple resistor. This in the schematics is the function of R1.

If you have stability problems, you can play with the value of R1 and to try to reach the stable operation. The input range of the opamp must include both voltages - the ground rail and the reference. I have designed the PCB in "Eagle". The design files can be downloaded.

I have used the following approach: The PCB is designed by the use of two conducting layers : bottom and top. If you want to order the PCB in the fab, you can use dual metal technology. The top metal layer connections are replaced by trivial wire bridges. A PDF file prepared for the toner transfer "lithography" is available also for download.

The same PCB after etching can be seen also. Here I show some pictures of the soldered PCB. The opamp is placed in IC socket. The power NMOS has its cooler mounted.

Instead the jumpers as in the schematic , I soldered directly wires. It has its own small housing with lenses, but for high power it needs additional cooling.

Special cooling housings are available on the market for example Ebay , but I have decided to make it by myself. For that purpose I have used some available materials : two aluminium coolers, a nut and bolt. At first I made a hole in the middle of the bigger cooler. After that I have shaped it by the use of round file to pass exactly to the LD placed in its original housing. I have found a nut, which was quite thick as the LD original housing bottom wall.

I filed it to have the same thickness. I have to made thinner also one of the side walls of the nut. The pictures show how it looks like after the filing and where it stays in the cooler. I took a small plate used as cooler, drilled additional hole for the LD terminal connection wires. The next step was to solder wires to the LD terminals. You have to check what is what of the terminals in the LD datasheet they can be as shown on the picture, but hey can be also arranged in different way.

I put a heat shrink cable sleeve on the positive wire to prevent accidental short circuit with the negative one. This is a 4. See all 2 brand new listings. Sold by goldy About this product Product Identifiers Brand. Show More Show Less. New New. Ratings and Reviews Write a review. Most relevant reviews. Best Selling in Laser Diodes See all.

Nichia TH Nichia Nugm02 nm 1w Green Laser Diode 5. All Listings. Accepts Offers. Buy It Now. Item Location. Canada Only. North America. Shipping Options. Free International Shipping. Local Pickup. Free Local Pickup. Show only. Free Returns. Returns Accepted.