Blue LED Transilluminator





Introduction: Blue LED Transilluminator

This instructable describes how to make a blue LED (470nm) transilluminator for DNA imaging using SYBR safe dyes. The transilluminator has a 6 x 7 cm viewing area for small agarose gels.

The transilluminator can also be modified to sit beneath the mini-gel electrophoresis tank (from a previous instructable), as described in Step 8. Used in this way, you can also visually track progress of your DNA during electrophoresis.

Open source hardware kit - This is an open source hardware project. To enable users to make or modify the device, I have included all of the PCB design files, enclosure design files and list of all hardware and electronics in a zip file attached below. We have also put together an LED Transilluminator Kit containing all of the parts described in this Instrucatble. 

Step 1: Kit Contents

Each blue LED transilluminator kit comes with the following parts:
  • Printed circuit board and electronics: DC jack, resistor, switch and 72 x blue LEDs
  • Laser cut parts: 6 x black acrylic parts, 1 x clear acrylic parts, 1 x LED diffuser, 1 x blue light filter and an amber lid
  • Enclosure hardware: 4 x male-female standoffs, 4 x 3/4" long standoffs, 4 x 1" long standoffs, 8 x screws and a mini-screwdriver
  • Power supply. 12V power supply with an output current of at least 0.25A. Optional addition to the transilluminator kit. We use one from Jameco Cat # 252824.
Note: A complete list of all of the parts for the enclosure and PCB are included in the zip file in the previous step.

Step 2: Soldering the Components Onto the LED Board

Solder the following through-hole components onto the LED Transilluminator PCB. Note: for an Instructable on soldering components onto circuit boards, check out How-to-solder (Steps 4& 5) by noahw.
  • 72 blue LEDs. Positions D1- D72. Make sure to check the orientation of the LEDs before soldering. The cathode of the LED is indicated by the flat edge on the silkscreen of the PCB. Insert the LED so that the short leg (cathode) is nearest the flat edge in the silk screen. See image.  
  • 5.6 Ohm resistor. Inset the resistor into either R1 or R2.  
  • DC jack. Insert into position P1.
  • Switch. Insert into position SW1.
Once all the components are in place, plug in the 12 V power supply and switch on the board to check all of the LEDs are working correctly.

Step 3: Assembling the Enclosure Bottom

Before starting assembly, peel off any of the paper backing from the laser cut parts. 
  • Take the enclosure base and attach the four small male-female standoffs using four of the screws
  • Place the PCB onto the 4 standoffs and screw in the 1" standoffs
  • Take the four threaded studs and screw them all the way into the 1" standoffs
  • Place the enclosure sides, enclosure back and enclosure front parts onto the enclosure base. Note that the four parts have short tabs on one side and longer tabs on the other side - place the parts so that the shorter tabs go into the base plate with the longer tabs are at the top
  • The enclosure back part with the cutouts should fit over the DC jack and switch as shown in the images.

Step 4: Assembling the Enclosure Top

Place the next 4 laser cut parts in the following order:
  • First: Light diffuser film (2 sheets)  
  • Next: Blue filter 
  • Next: Black enclosure top (with the square cutout)
  • Last: Clear enclosure top (with engraving) 
Edit: A list of all of the acrylic materials used in the enclosure and the filters are listed in the file "BOM_enclosure.txt" in the "enclosure" folder of the zip file (see Intro). List includes suggested vendors and part numbers.

Step 5: Assembling the Amber Top and Testing

  • Screw the 4 remaining 3/4" standoffs onto the enclosure
  • Place the amber lid on top and secure in place with the 4 remaining black screws.
You have finished assembly of your transilluminator ! To test the transilluminator, plug in the power supply and switch it on. 

Step 6: Preparing a SYBR Safe Agarose Gel

Materials and Equipment
  • Mini-gel electrophoresis tank or similar
  • 1% agarose in TAE buffer (e.g. Melt-n-Pour Agarose, Carolina Biologicals, Cat # 21-7085)
  • 1 x TAE buffer (e.g. diluted from 50x stock from Carolina Biologicals Cat # 21-9033)
  • SYBR Safe DNA gel stain (Invitrogen Cat # 915548)
  • Tape 
  • Micropipette
  • DNA samples
  1. Seal the ends of the gel tray with the tape and place the gel comb in the slots of the gel tray. Place the tray on a flat surface.
  2. Melt the agarose in the microwave and let stand to cool until the bottle is warm enough to hold. Pour 50 mL of agarose into a small beaker.
  3. The SYBR safe stain is a 10,000 x stain. For 50 mL, add 5 µL of SYBR safe stain. Swirl the beaker to mix.
  4. Pour the agarose into the gel tray and let it cool and set (10 mins at room temp)
  5. Carefully remove the tape from the ends of the gel
  6. Place the tray in the tank filled with buffer
  7. Carefully remove the gel comb
  8. Pipet your DNA samples into the wells
  9. Place the lid onto the tank and connect the electrodes using banana cables
  10. Run the mini-gel at 50-100V. This takes approximately 30-60 mins.

Step 7: Viewing the Gel

Once the gel has finished running, take it out of the tank and place it onto the transilluminator. Switch on the LEDs - you should be able to see your DNA. In this image I have loaded 10-20 µL of a 1Kb DNA ladder (NEB QuickLoad, 50µg/mL). 

Step 8: Viewing Gels During Electrophoresis

The transilluminator can be easily modified to use used with the mini-gel electrophoresis tank to view DNA during electrophoresis. 
  • Unscrew and remove the amber filter
  • Unscrew and remove the 4 x threaded studs
  • Place the 4 screws in each corner to hold the enclosure together
  • Replace the clear tank lid with a lid cut from amber acrylic. Alternatively, place the amber from the transilluminator on top of the clear lid
  • Place the transilluminator under the gel box. You should be able to see your DNA bands shortly after they have run into the gel.



  • Epilog Challenge 9

    Epilog Challenge 9
  • Sew Warm Contest 2018

    Sew Warm Contest 2018
  • Paper Contest 2018

    Paper Contest 2018

We have a be nice policy.
Please be positive and constructive.




Thank you very much. Your project is great. I wonder if you can tell me what led do you use because I've tried standard blue leds (I think they are 465-470 nm) and it wasn't enough to see SYBR green.

Anyway, thank you

Dear jorodeo
Thanks for yuor fantastic instructions.
I made a blue led transilluminator like yours. But its doesnot work!
I stained dna with syber green and it glue under uv light but dose not under blue led light. What do you think?!
How I can fix this problem?

Electrophoresis Dna Fingerprinting
- We are specialized in Gel Documentation System and we also focus on Electrophoresis of DNA and Electrophoresis DNA Fingerprinting.
visit here :-

This is a great idea! I've been wanting to build an LED based illuminator for a while now. Especially for sub-cloning and gel extractions.
We currently use A hand held UV light which can damage DNA and myself, so this 'ible is a much safer and effective tool.

dear jorodeo,
please follow the link and kindly let me know why this blue led transilluminator is optimized for varied stains where as why not the model you have specified.

Srinivas J

It looks great. We're looking at getting something like this to replace EtBr+UV and it looks perfect. Except for the size. Do you have any plans to make a slightly larger one? (For 10cm gels)

Hi jorodeo,
congratulations to this instructable of yours. It is excellent, as the previous ones.
I have a question about DNA staining with SybrGreen. Apart from obvious health safety, are there any technical advantages or pitfalls, when compared to conventional Ethidium Bromide staining?

Hi Isacco,
That is a really good question. From what I know, the safety concern with ethidium bromide is really the big difference. In addition, UV can damage DNA which is not good obviously for cloning, sequencing etc. Having said that I used ethidium bromide for donkeys years in the lab and only recently switched to Sybr safe as I am no longer in an academic lab with access to endless piles of disposable gloves and convenient hazardous waste disposal.

As far as technical advantages and pitfalls, I should note that I use Sybr safe, not Sybr green. From what I have read from the literature, Sybr safe is reported to have a comparable sensitivity to ethidium bromide. I use the gel stain version - add it to the agarose before microwaving etc. so technically it handles very similar to ethidium bromide. I did notice that you can't re-use the gel though, which I have done with ethidium bromide gels. So far I haven't any problems with using Sybr safe. Cost is about $0.70 per gel versus pennies (?) for ethidium bromide. I would say it comes down to what you have access to in terms of waste disposal, type of transilluminator etc. and downstream application of your DNA where the advantages of not exposing your DNA to UV may be important.

I hope that helps !


Great !
I often see DNA with 254/302 nm UV transluminator and Etbr
I want to have one but I 'm in Vietnam
What materials of Blue filter ? Can i use blue arylic?

Hi qmap,
I have another instructable on making a UV transilluminator for this purpose ( which works really well. However, as ethidium bromide and UV are not the friendliest tools to work with (especially in educational settings) I also wanted to make a blue light/sybr safe version.
For the blue filter, I tried a couple of different materials looking for something that can be laser cut and is not too expensive - this is blue acrylite # 668-0 which I bought online from, part # 5C028GT.
I have just edited the enclosure bill of materials (found in the zip file in the Intro) to include a list of all of the acrylic with vendors/part numbers.
By the way, if you want a kit, I'm sure we can ship to Vietnam ;)