UV Transilluminator





Introduction: UV Transilluminator

UV-transilluminators are used in molecular biology labs to view DNA (or RNA) that has been separated by electrophoresis through an agarose gel. During or immediately after electrophoresis, the agarose gel is stained with a fluorescent dye which binds to nucleic acid. Exposing the stained gel to a UVB light source causes the DNA/dye to fluoresce and become visible. This technique is used wherever the researcher needs to be able to view their sample, for example sizing a PCR product, purifying DNA segment after a restriction enzyme digest, quantifying DNA or verifying RNA integrity after extraction.

This Instructable tutorial describes how to make a UVB (310nm) transilluminator with a 7 x 7 cm window for viewing ethidium bromide (or SYBR-Safe) stained DNA mini-gels. Once all of the materials are collected, the actual assembly time is approx. 1-2 hours. Some soldering is required.

Safety Notes:

  1. Because ethidium bromide is a toxic chemical with strict safety protocols, it is only recommended that you use this dye in a lab with established handling, storage and waste disposal procedures in place. Other users are strongly recommended to use SYBR-Safe instead, which can be handled and disposed of more safely.
  2. The transilluminator does come with a safety lid for viewing the gel. However, when the lid is not in place, safety glasses mustbe worn when operating the UVB bulb.
  3. If you prefer to avoid UVB altogether, we can recommend the blue light LED transilluminators such as the one described in this instructable instead.

Step 1: Materials: Laser Cut Acrylic Parts

For the UV transilluminator enclosure and lid, download the design file attached below (svg or PDF file). Laser cut the parts from the material listed in the design file. If you do not have access to a laser cutter, you can send the files to any laser cutting service such as Pololu. Materials for laser cutting can be found at any supplier of acrylic materials (McMaster-Carr, US Plastics etc) except for the solacryl (UV-transmissive) which can be bought from Loop Acrylics.

Tap holes in the following parts:

  • 5-40: Two holes in the enclosure side with the cutout for the power switch
  • 8-32: Four holes in the solacryl cover
  • 8-32: Four holes in the 0.25" clear lid side part for mounting the hinges
  • 8-32: Two holes in the enclosure bottom

A video of hand-tapping acrylic can be found here: https://www.instructables.com/id/Gel-electrophoresis-system-mini/step2/Comb-assembly.

Step 2: Materials Contd: UV Bulb, Filter and Other Hardware

1 x 312nm Ushio 9W GPX9E UV bulb Cat # 11_2122, Fotodyne: http://www.fotodyne.com
1 x ballast and G23 lamp holder Cat # 163141.02, Atlanta light bulbs: http://www.atlantalightbulbs.com/
1 x U325C transilluminator glass, 7 x 7 cm, HOYA Corporation:http://www.hoyaoptics.com/color_filter/index.htm
1 x power entry and switch. Cat # CCM1906-ND, Digikey: www.digikey.com
1 x 6' power cord. Cat # 132118, Jameco: www.jameco.com

4 x Plastic Bumper. Cat # 9405K61, McMaster-Carr: www.mcmaster.com
4 x 10-32 standoff, 2.5” long. Cat # 92230A140
4 x 10-32 machine screw, 1” long. Cat # 91249A272
4 x 10-32 machine screw, ½” long. Cat # 91249A263
2 x 5-40 Thread, ½" long. Cat # 91772A128
2 x 8-32 Thread, ¼" long. Cat # 91772A190
8 x 8-32 machine screw, 3/16” long. Cat # 91771A189
2 x Hinges Cat # 1598A52
2 ft x 14 Gauge general purpose wire. Cat # 7587K98

1 x IPS weld-on cement #3 or 4, Cat # 10792, TAP Plastics: www.tapplastics.com
1 x Hypo-type solvent cement applicator, McMaster-Carr, Cat # 25658


  • Philips screwdriver
  • Soldering iron and solder
  • Wire clippers

Step 3: Connect AC Power to Ballast

  1. Place the power entry and switch into the laser cut back part and secure in place with the two 1/2" long 5-40 machine screws.
  2. Connect neutral and live wires to ballast as shown in the images
  3. Solder the neutral wire and live wire to the plug connector as shown in the images.

Step 4: Assemble the Enclosure

  1. Take one of the 1" long 10-32 machine screws and thread it through one of the rubber feet and the corner holes on the bottom enclosure part. On the opposite side of the enclosure, screw in one of the 2.5" long 10-32 standoffs. Repeat for all 4 corners of the enclosure bottom.
  2. Place the ballast in the middle of the enclosure and fasten down with two of the 1/4" long 8-32 screws. Make sure that the ballast is oriented as shown in the images.
  3. Put the UVB bulb into the ballast and place the remaining enclosure parts into the slots in the enclosure bottom.

Step 5: Assemble the Cover

The top part of the transilluminator includes the transilluminator glass covered with the solacryl UV-transmissive protective cover.

  1. Place the lower lid onto the top. It will be secured in place by fitting it over the tabs on the enclosure sides.
  2. Lay the upper lid onto the lower lid.
  3. Place the transilluminator glass into the slot on the upper lid.
  4. Place the UV-transmissive protective plate over the enclosure.
  5. In each corner screw in the four 1" long 10-32 machine screws to secure all 3 top layers plus transilluminator glass in place.

Step 6: Assemble the Hinged Safety Lid

In the final assembly steps we will add a hinged safety lid. The top part of the lid is 1/8" clear acrylic which will block UV light. (Note: you should use safety glasses if you will be operating the transilluminator at any time without the lid.)

  1. Using the Weld-On acrylic glue and applicator, weld the 1/4" acrylic sides onto the 1/8" base.
  2. Attach the two hinges to the lid using four of the 3/16" long 8-32 machine screws.
  3. Attach the hinged lid to the top of the enclosure as shown using the remaining four 1/8" 8-32 machine screws.

Step 7: Viewing a Gel

Preparing an electrophoresis gel is a whole other tutorial so for now I would recommend reading this excellent Instructable for preparing the gel:

and this Instructable for making your own electrophoresis system:

Once you have your gel prepared, place it onto the transilluminator above the viewing window, put the hinged safety lid down and switch on the transilluminator. At this point you should see your DNA bands.



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    Hello im wahyu.
    So i want to buy this product. How i can order. I'm from indonesia student pharmacy faculty unv. Mulawarman

    Hi friends. We are doing a physics project and in order to laser cut our platform with a CAT program we need the original dxf/dwg file. If you could reply with this file, we'd really appreciate it! Thank you in advance, Hanako

    Hi Hanakokurita. Apologies for the last response. I have added a zip file under Step 1 called "uv_trans_parts.zip" which contains the dxf files for making the enclosure. Thanks !


    I greatly appreciate your work!

    My idea is using black (Wood) light (with wave length maximum around 310 nm or shorter - this of course is rare lamp to find but it exists). What do you think about it? And if I have some luck in finding this type of a lamp: the question is how to disperse the light of this lamp, to illuminate sample properly? Is there diffuser for UV light radiation.

    And after all: where do you advise me to buy "second-hand" UV-transilluminator - or new (not brand mark) for students' laboratory.


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    Hi, Jorodeo
    Where I buy U325C glass ?, Because of in Thailand not have it.

    Terrific instructable! This looks like it works. The sub-$100 transilluminator is a milestone. Great job in particular explaining how to use the professional-grade 312nm UVB bulb and ballast (only $28 for the bulb! awesome! Cat# 11-2122 at http://www.fotodyne.com/content/trans_access).

    I have experimented with making my own transilluminator for GelGreen and SybrSafe stains, similar to the Pearl Biotech transilluminator instructable you linked to. I have found that 2424 Blue Acrylic works as prefilter and 2422 Orange Acrylic works as a postfilter for those stains. I got sample sheets from ridout plastics.  Attached is a photo of a gelgreen-stained dye sandwiched between these two acrylics illuminated underneath via a blue LED array.

    Any interest in working on a design for open-source reusable gel cassettes for making precast gels?  It would be possible to create these cassettes directly out of the filtering acrylics.


    is this acrylic sheet are completely dull or light transmitting?

    Thanks for your comments. I actually had a lot of fun building it once I was able to source all the parts. I've used commercial UV transilluminators for years and they are so expensive ! Your version with leds and blue/orange acrylic filters looks like it works well too. I have toyed with the idea of having a second set of parts which would convert the UV transilluminator into a blue/orange version. In theory I guess you could swap the UV bulb for the white light version ($15 from fotodyne) and instead of the transilluminator glass use the blue acrylic, and then make the lid from orange acrylic ? I should try that. Thanks for sharing your acrylic sources and sample gel image.

    I would be interested in the gel cassettes. Have you get some ideas for this project already ?

    Please excuse my naivete but you've chosen the filter because it transmits wavelengths in the absorption range of the ethidium bromide (around 300nm) and also transmits in the emission range of the ethidium bromide (around 700nm) as well, correct?

    In the picture above, were the bands visible to the naked eye or did you have to use a UV camera to get them to show up?

    Also, does this transilluminator fit under your (mini) gel electrophoresis system so that you can see the bands while the electrophoresis is running?

    Sorry for the deluge of questions, thanks again for the great instructables!