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Our Newsletter

Tesla Parts and Accesories


Toroids, Oblates and other terminals

Special note on toroid construction: the toroids we sell are intended to be used for Tesla coil capacitive terminals. These pieces are brushed aluminum, and if used for high-voltage DC applications they must be highly polished to almost a mirror finish. But for Tesla coil applications they do not need this smoothness or polish, only for aesthetics if the user wants this look. Polishing will either add more to the cost or take time if you want to do this yourself, but will not improve the performance of a tesla coil.

There is nothing more pleasing to the eye than a high-performance Tesla coil emitting arcs and sparks from a properly sized toroidal terminal. Our aim is to offer these parts as economically as possible to the Tesla coil or high voltage builder.

Please contact us if you would like your toroids to be polished.

Toroidal Terminals For HV Uses
Ready to use for Tesla coil and other high-voltage applications. If these will be used for high-voltage DC stacks or multipliers, they will need to be polished to a shiny mirror-like surface (you can do this yourself, or have it done for you).

Our laboratory has the tooling and now offers many sizes of toroidal terminals from 3" to 98". Have a look at our PDF sheet to see other available sizes from 3 to 98 inches!

These are spun aluminum of grade 1100-O (99% pure aluminum), with a welded seam on sizes above 12" that is smooth and cannot be seen. Aluminum wall thickness is approximately 1/16" (so the flat central area is about 1/8" thick, for example).

Excellent for Tesla coils requiring a capacitive terminal, and high voltage DC generators up to 1.5 million volts. (Note that high voltage DC generators require a highly-polished surface to prevent leakage losses, which is contrary to Tesla operation where you want air leakage to make the sparks. High voltage DC generators should also use seamless toroids as these are easier to finish to a smooth mirror-like surface.)

Toroidal terminals used for Tesla coils are for producing a capacitive load that lowers the impedance of the output, consequently giving a hotter and brighter spark. These pieces do not require smooth or shiny surface as do toroids used for high-voltage DC power supplies where smoothness is mandatory to prevent high-voltage Corona leakage.

Quantity discounts available. View free PDF sheet for other available sizes.

Free PDF sheet
available sizes up to 98"
TO8 - For coils up to 250kV, 8"x 2" with ¼" Center Hole (visible seam) ... $53.50
TO12 - For coils up to 500kV, 12" x 3" with ¼" Center Hole (visible seam) ... $89.50
TO18 - For coils up to 750kV, 18" x 4.5" with ¼" Center Hole (no seam) ... $312.50
    TO18N - The 18" toroid (with a visible seam) ... $169.95
    TO18P - The 18" toroid (no seam & highly polished, intended for Van de Graaff) ... $494.95
TO20 - For coils up to 850kV, 20" x 5" with ¼" Center Hole (no seam) ... $369.95
TO24 - For coils up to 1Mev, 24" x 6" Welded with ½" Center Hole (no seam) ... $469.95
TO30 - For coils over 1Mev, 30" x 7" Welded with ½" Center Hole (no seam) ... $645.95
TO36 - For coils up to 1.5Mev, 36" x 6" Welded with 1/2" Ctr Hole (no seam) ... call or email
TO40 - For coils up to 2Mev, 40" x 10" Welded with 1/2" Ctr Hole (no seam) ... call or email
TO68 - For coils up to 2Mev, 68" x 18" Welded with 1/2" Ctr Hole (no seam) ... call or email

Shipping: these are bulky items and shipping may exceed the website calculation for 20" and larger toroids. Please contact us, or we will let you know after your order has been placed if any additional shipping is required.

click to enlarge

Aluminum Oblate Terminal
Oblate Terminal We now can offer the high voltage researcher a 14-inch terminal that supports up to 500,000 volts. The 14" diameter (9" across the oblate) has a 3-3/4" hole for mounting onto an insulated column and can be used for the collector terminal of a Van de Graaff generator.
OBLATE14 - 14" Aluminum Oblate Terminal ... $249.95

3+ @ $199.95ea.

Neon sign Transformers designed for Tesla coils

Original built neon Transformers are almost perfect for use in small Tesla coils. The impedance matches readily available capacitors that form resonant circuits that are easily coupled to the resonant secondary coil. The only problem with the original neon sign transformer is it was not designed to support the open circuit voltage. When powering a gas discharge tube, the voltage would drop and quickly stabilize to the negative resistance of the gas discharge. When a neon transformer is used in a Tesla coil great care must be taken to prevent the sustained high-voltages now across the transformer. These are accompanied by RF currents and other transient's that can breakdown the original insulation that the transformer was never designed for.

Our engineers gave it a lot of thought and said why not use the already existing tooling, cases and all the other readily made fabrications, core, coils etc. etc. used for a conventional neon transformer and build in the extra beef and add some type of a filtering network that would prevent sustained high voltage breakdown. To make a long story short we had our transformer made by a company that was very cooperative with our request and proceeded to make these Transformers under our design parameters for the output. It took two tries but we can now say to run these Transformers for a Tesla coil only requires a simple 300 to 1000 ohm 25 W wire wound resistor that now greatly simplifies construction. Conventional neon sign transformers for reliable operation require our suppressor circuit that is not a big deal but does add to the construction and cost. This is eliminated when using our proprietary designed Transformers that incidentally are private labelled.

Designed and built for use in Tesla coil applications as stated in download. Brand new and only require two resistors for reliable operation. Easily combined for 220 volt operation by series connecting primaries and parallel connecting the secondary’s.
15kv 60ma transformer

15kv 60ma transformer 15kv 60ma transformer

We have now have our own 15000 volt 60 ma current-limited transformers. These are brand new, factory-fresh transformers specially made for Tesla coils (and also work with JACOB’S LADDER and HIGH VOLTAGE POWER SUPPLIES and many other high-voltage applications. See download for more data.

They do not contain the GFI that is necessary for UL 2161 when used for neon sign applications therefore they should not be used for neon installs. These do not require the suppression circuits that normal neon Transformers do when used for Tesla coils except for two 300 to 1K 25 watt resistor on each electrode. You can run two units in parallel this way. If you use more it is suggested using our SUP10 suppression circuit.

Notes: These operate from 115 vac, and up to 6 are easily parallel connected for higher power operation. Six units connected in this way can produce 15000 vac rms at 360 ma. This is enough power to make a large TESLA coil easily producing 10+ foot arcs (such as our BTC70). May also be connected for 7500 volts at 720 ma

Center point grounding can produce dangerous ground currents. Follow all safety rules dealing with high voltages. All transformers are open circuit tested at 1.2 x 120 vac for six hours before shipping.

Units are 10.75 x 6.4 x 5.25" and weigh 42 lbs. (Note that shipping weight is approximately 52 pounds and may exceed our website's estimation -- our shipping department will let you know if it is more, or please contact us by phone or email if you would like to know in advance.)

15KV/60MA-TC - 15kv 60mA non-GFI Transformer (includes BTC5 plans) ... $349.95

Current-Limited HV Transformer at 30ma and 6KV
6kv 30ma transformer

6kv 30ma transformer

Centerpoint grounded secondary, current limited, encased unit with screw terminals. All connections are internal: remove cover to access, then push out a metal chad according to your location preference for running the input and output wires. This transformer is excellent for small table top Tesla coils. Dimensions: 10.75" (12.5" at feet) x 4" x 6.5” with a weight of 17lbs.

Please note: this transformer has the 6KV 30mA output required by our BTC30 tesla coil, but it is physically too tall to fit into the base area. The height of the BTC30 base area could be increased, however that is a modification you would need to undertake.

Shipping weight may exceed the website estimate -- we will contact you if any additional amount is required.
6KV/30LEC - 6kV 30mA non-GFI Transformer with Switch only ... $69.95
6KV/30LEC-RB - 6kV 30mA non-GFI Transformer with Switch and Reset Button... $69.95

Designed and built for use in neon lighting applications. Unused but may require our SUP10 Suppressor shown in our store for reliable operation. May also be used for JACOBS LADDER displays without suppression circuits. Great for high voltage supplies. Many available voltages at the standard 60 ma. values. These units do not have GFI s. Most in original boxes.

5000 volt 60ma will generte almost 1.5 foot streamers in a properly designed TESLA coil system.

This transformer can produce over a 1” impressive flaming hot arc when used for a Jacobs ladder.

Use for DC power supply Full Br 5kv60ma / Half Br 2.5kv120ma using our VG15KV200 rectifiers

Two styles to choose from Original ALLISON and MAGTEC Sizes

5KV60MAG13 ....... $79.95

4000 volt 60ma will generate almost 1 foot streamers in a properly designed small TESLA coil .

This transformer can produce an impressive flaming hot arc when used for a small Jacobs ladder.

Use for DC power supply Full Br 4kv60ma / Half Br 2kv120ma using our VG15KV200 rectifiers

Original ALLISON Size

4KV60ALL11 ....... $59.95

3000 volt 60ma will generate impressive streamers in a small TESLA coil suitable as a desk piece

Can produce a traveling arc when used for a small Jacobs ladder but may be finicky to set up.

Use for DC power supply Full Br 3kv60ma / Half Br 1.5kv120ma using our VG15KV200 rectifiers

Original ALLISON Size

3KV60ALL13 ....... $49.95

All purchases include our BTC3 Tesla coil plans and a secondary protection circuitry schematic when used for TESLA COILS as suggested by the late DC COX of RESONANCE RESEARCH. The 60 milliampere transformers will require down loading our hazardous equipment affidavit

Safer 30ma Neon Signs Transformers
Designed and built for use in neon lighting applications. Unused but may require our SUP10 Suppressor shown in our store for reliable operation. May also be used for JACOBS LADDER displays without suppression circuits. Great for high voltage supplies. Less display than above 60ma units but safer to use. These units do not have GFI's. Most in original boxes

You must call to order these as limited 603-673-4730

Order-4KV/30-1 MAGTEK……………………………….$34.95

Order-7.5KV/60-2 MAGTEK……………………………….$74.95

Order-9KV/30-1 ALL……………………………….$69.95

Order-9KV/60-2 ALL……………………………….$99.95

Pole Transformer
14.4KV Pole Transformer

Heavy duty 14.4kV (very conservatively rated), 1- or 2-bushing oil filled unit, running on 120/240VAC input. Good for Tesla Coils, up to 20 ft. discharges! Great for many other scientific experiments and industrial applications. Sold only to qualified researchers and labs.


A Hazardous Equipment Affidavit must be signed before these items can be released (see link below).

3KVA14.4KV - 3 KVA 14.4 KV Pole Mount 120/240 1PH 1 Bush AL Wire ... call for pricing
            ~250lbs, 42"H x 14.5"D (21" w/attachments)
5KVA14.4KV - 5 KVA 14.4 KV Pole Mount 120/240 1PH 2 Bush AL Wire ... call for pricing
            ~250lbs, 42"H x 14.5"D (21" w/attachments)
7.5KVA14.4KV - 7.5 KVA 14.4 KV Pole Mount 120/240 1PH 2 Bush AL Wire ... call for pricing
            ~250lbs, 42"H x 14.5"D (21" w/attachments)
10KVA14.4KV - 10 KVA 14.4 KV Pole Mount 120/240 1PH 2 Bush AL Wire ... call for pricing
            ~330lbs, 42"H x 14.5"D (21" w/attachments)
15KVA14.4KV - 15 KVA 14.4 KV Pole Mount 120/240 1PH 2 Bush AL Wire ... call for pricing
            ~460lbs, 34.5"H x 18.5"D (24" w/attachments)
25KVA14.4KV - 25 KVA 14.4 KV Pole Mount 120/240 1PH 2 Bush AL Wire ... call for pricing
            ~570lbs, 37.5"H x 16.5"D (23" w/attachments)
50KVA14.4KV - 50 KVA 14.4 KV Pole Mount 120/240 1PH 2 Bush AL Wire ... call for pricing
            ~870lbs, 48"H x 25"D (31" w/attachments)
Please contact us for current pricing and availability, or for any other questions on these items.

Air Cooled Two Point Spark Gap for Tesla Coils up to 8’ Sparks
Spark Gap Switch Excellent for Tesla Coils up to 48" Discharges

Intended for Tesla coils power up to 15Kv at 180ma. Available with 3/8" machined tool steel or pure tungsten electrodes. Functions at 60 to 100 breaks/second. There are 3 electrodes: the 1 center electrode is 2.5" length; the 2 side electrodes are each 2" length. 115 Vac is required for the high output fan. Ready to use with connection lugs. Size is 5 x 5 x 4". Our BTC40, 50, and 60 use this setup.

Use two in series for a four point gap for Tesla power up to 15kV at 400ma producing up to 15’ sparks. Our BTC70 uses this setup.

SPARK1 - With 2 x 3/8" Tungsten Electrodes ... $149.95
SPARK1TS - With 2 x 3/8" Tool Steel (not Tungsten) Electrodes ... $59.95

Convection Cooled Single Gap System for Small Coils With power to 8Kv at 60ma
Spark Gap Switch Excellent for Tesla Coils up to 12"

Intended for Tesla coils up to 9kV at 60ma. Uses ¼" pure tungsten electrodes mounted on aluminum heat dissipating fins. Horizontal retaining screws provide easier access and adjustment of spark gap width. Base is polycarbonate with mounting holes. Includes high current connection lugs. Size is 5½" x 2 x 2". Used in our BTC30 giving 14” sparks.

SPARK05 - With ¼" x 1" Tungsten Electrodes ... $59.95

We also carry solid copper block holders or the more attractive PANDUIT holders. We tested for temperature rise and peak current and found no difference between the lower cost aluminum or copper holders.

1/4" x 1" Pure Tungsten Electrodes Coils up 7500 v 60 ma
coil gun

With connecting mounting blocks and terminations, or individual tungsten rods only Precision machined and faced. Self cleaning and cool running, will not oxidize. May be connected in series for multiple gaps handling greater power

TUNG141EP - 1/4" x 1" Tungsten Electrode Pair with Mounting Blocks ... $39.95
TUNG141 - One (1) Tungsten Electrode 1/4" diameter x 1" length ... $14.95

3/8” x 2” Pure Tungsten Electrodes 15000 v 120 ma
coil gun

With connecting mounting blocks and terminations, or individual tungsten rods only Precision machined and faced. Self cleaning and cool running, will not oxidize. May be connected in series for multiple gaps handling greater power

TUNG38EP - 3/8" x 2" Tungsten Electrode Pair with Mounting Blocks ... $89.95
TUNG38 - One (1) Tungsten Electrode 3/8" diameter x 2" length ... $39.95

Specialized Capacitors for High Power Tesla Coils
These highly reliable capacitors are for museum displays, research, and professional applications where reliability is a premium. There are lower cost alternatives that use MMC and other options for this part, and these less costly choices are perfectly suitable for the hobbyist and experimenter. But when reliability matters, these are the capacitors to use.

These specialized capacitors are made for Tesla coil applications where high frequency and high current operation is required.

Capacitors are constructed with a polypropylene dielectric being specially wound to reduce corona and have a high voltage standoff capability. Capacitors are also designed to withstand the multiple discharges of a rotary gap system of up to 600 breaks per second with a suggested operating frequency of 30 kHz.

(Please note that the "10KV Max" printed on the shell refers to the shell strength: this is the maximum hit the shell can withstand if a high-voltage component were to discharge directly through the shell. But the label on the capacitor shows the maximum operating voltage that the capacitor will safely handle when it is properly connected & voltage discharges through the end terminals as intended.)

Capacitors are enclosed in a high impact PVC tubing and epoxy sealed with axially positioned terminals. Several values are available to match with transformer input. (For example, the .05u/20KVAC provides an excellent combination when used with the readily available 14.4 kvac pole transformer in the 7 to 10 kva range. One capacitor will utilize one half this kva range while two in parallel with utilize the full rating and produce in excess of 12 foot discharges.) We use these capacitors in our tesla coils, such as the .01u/10KVAC-S in our BTC30 tesla coil, and the .014u/20KVAC-S in our BTC40 tesla coil. Many other values are available; please contact us if you need a specific design for a custom coil or other application.

.01u/20KVAC - .01µfd at 20KVAC, 3-½" x 14" cylindrical ... $279.95
.014u/20KVAC-S - .014µfd at 20KVAC, 1.5" x 4.3" cylindrical (used in our BTC45) ... $79.95
    .02u/10KVAC - .02µfd at 10KVAC, 2-3/8" x 7-½" cylindrical (used in our pre-2012 BTC40) ... $189.95
.05u/20KVAC - .05µfd at 20KVAC, 6-5/8" x 14-½" cylindrical (used in our BTC70) ... $699.95
.075u/25KVAC - .075µfd at 25KVAC, 5-1/2" x 12" cylindrical ... $659.95
.1u/20KVAC - .1µfd at 20KVAC, 6-5/8" x 22" cylindrical ... $739.95

Tesla Coil Low Cost MMC Capacitors
Intended for the hobbyist and applications with stringent reliability factors. These capacitors were tested along with the equivalent CDE unit many builders are now using. We found no difference in performance or operation either for spark or the primary capacitor for DRSSTC high powered coils.
Individual 1.5u 2kv MMC Capacitor

Example of a 15-Capacitor Array

Our .15ufd 2000volt metallized polypropylene film and film foil capacitors are built into a rectangular enclosure and fully potted. The value of this capacitor is identical to the Cornell Dubilier 942C20P15K-F. When tested against this part, it was found that they performed identically. There were no breakdowns in either capacitor when used in similar circuits. We than ran both capacitor modules by reducing the number in series and keeping the spark gap voltage the same (6000V RMS AC 60Hz 30mA), to find out when breakdown would occur. We did this with 10 units of each, and there was no statistical difference between this capacitor and the CDE in the breakdown and failure points. We were very pleased at the outcome and performance of these capacitors. NOTE that the volume of this capacitor is 50cm2, whereas the CDE is 31cm2.

Our capacitors are built into a rectangular enclosure of PVC 4.3cm x 3.3cm x 3.5cm with a wall thickness in excess of 1/16 inch. They are completely potted with the leads exiting at the top of the epoxy very close to the ends. This makes it very convenient when attaching these capacitors in a series configuration by simply parallel connecting the 18 gauge leads, therefore doubling up on the conductance of the connections and greatly simplifying the attachment process. The capacitors can be mounted on a flat piece of PVC or other substrate and do not require holes drilled and the long lead legs like when using the axial CDE capacitors. This in itself reduces the assembly time and greatly improves the quality and aesthetics of the completed module. Voltage balancing resistors are now easily connected to the assembly to finish it off. You have the option of gluing the capacitors in place or securing them with nylon tie wraps, tape, or similar. You can then parallel the rows: as an example, 15 capacitors can be mounted in series in three rows of five each and make for a nice compact good-looking package as seen in the photo. So far the first batch 1500 pieces went out in july and so far no failures reported other than some minor assembly problems that were quickly quelled

.15u/2KVMAZ1 - metallized polypropylene film and film foil capacitor ... NOW IN STOCK, READY FOR ORDER, (1-9) @4.50 ea (10-24) @ $3.95ea, (25-49) @ $3.45ea, 50+ @ $2.95ea

Fully Prepared Secondary Coils

Wound, Coated, and Ready to Use

All coil forms used are thin wall TYPE1 PVC and before winding are cleaned inside and out with a suitable solvent. They are then placed in a special vacuum chamber that will accommodate up to 10 coils (depending on size of course). This chamber is fitted with 10 microwave magnetron's properly spaced to provide homogenous heating to the PVC driving out the moisture with the vacuum system pumping it out. We find this method appears to enhance performance but we have no real documentation to make comparisons with. We feel it's a good start.

The form is then given a coat of polyurethane and wound on our programmable auto feed. Wire used in a heavy thermalize (optional colors of gold, red, green, and blue are available) Several coats of polyurethane each coat allowing to fully dry before the application of the next coat is applied.

BTC30 Secondary Coil

BTC3COIL: 13" high, 3.5" diameter, 1/8 thick low-loss treated PVC. Wound with #24 heavy magnet wire with 443 turns. Inherent resonant frequency is ~500kHz freestanding without terminal.

BTC3COIL-12 - 12" Wound Secondary Coil ... $129.50

BTC40 Secondary Coil

BTC4COIL: 20.5" high, 4-5/8" diameter, 1/8 thick low-loss treated PVC. Wound with #24 heavy magnet wire with 780 turns. Inherent resonant frequency is ~200kHz freestanding without terminal.

BTC4COIL-20 - 20" Wound Secondary Coil ... $179.50

BTC50 Secondary Coil

BTC5COIL: 21.5" high, 4-1/4" diameter, 1/8 thick low-loss treated PVC. Wound with #22 heavy magnet wire with 650 turns. Inherent resonant frequency is ~150kHz freestanding without terminal.

BTC5COIL-21 - 21" Wound Secondary Coil ... $179.95

BTC60 Secondary Coil

BTC6COIL: 33" high, 6" diameter, 1/8 thick low-loss treated PVC.

BTC6COIL-33 - 33" Wound Secondary Coil ... $449.50

BTC70 Secondary Coil

BTC7COIL: 48" high, 8-5/8" diameter, 1/8 thick low-loss treated PVC. Wound with #18 heavy magnet wire with 1020 turns.

BTC7COIL-48 - 48" Wound Secondary Coil ... $999.50

Whirling Spinner for Tesla Coils

Place this spinner on top of your tesla coil (works on core & coil, solid state, and vacuum tesla coils alike) and watch the sparks shoot out of the tips of the spinner as it begins to turn. Since the electrons are mutually repelled from each other, this forces them to travel down the arms and be emitted at the pointed ends, causing this well-balanced rotor to spin at increasing speeds, emanating sparks as it goes.


Several spinners are available for different-sized tesla coils -- please choose the spinner best-suited to the coil you are using. The N124 also includes accumulating disk and offset wand for use on Van de Graf generators, which causes a similar spin but at reduced speed and minimal sparking from what tesla coils can produce.

A fun accessory for your tesla coil!     spinner spinner spinner
BTC3040SPINNER - suited for BTC30 and BTC45 Tesla Coils ... $24.95
BTCSPINNER-N124 - suited for BTC30 and BTC45 Tesla Coils, and Van de Graaff Generators ... $49.95
BTC6SPINNER - suited for BTC60 Tesla Coils ... $99.95
BTC7SPINNER - suited for BTC70 Tesla Coils ... $249.95

Vacuum Tubes
vacuum tube

Brand new and unused power triode vacuum tubes for our VACTESLA10 vacuum tube tesla coil. (The 833C carbon vacuum tubes can withstand higher operating temperatures than the standard metal-based 833A vacuum tubes.)

This vacuum tube is used in our VACTESLA10 tesla coil, and it is listed here if a replacement is needed, or if you are making your own vacuum tube tesla coil. Dimensions are 8.75" height x 4.5" outer diameter.

Please note: these glass items are fragile and therefore cannot be refunded or returned -- all sales of this item are final. If there is damage upon receipt, you will need to file an insurance claim with the shipping company (approximately 1 in 100 orders are damaged from shipping). Please be aware of these limitations and requirements before ordering this item.

833A - Power Triode Vacuum Tube ... $189.95
833C - Power Triode Vacuum Tube Carbon ... $204.95

High Power IGBT (Insulated Gate Bipolar Transistors) 1200A 1700V
Used but tested to full specs. Extras from a US NAVY contract that originally required 500 peices.
vacuum tube

High power 600A 1200V dual switch, or highest power 1200A 1700V dual switch.

Each of the FF600R12KE3 modules contains two 600 amp 1200 volt IGBTs intended for use in a half-bridge circuit (the FF1200R17KE3 has two 1200 amp 1700 volt IGBTs), or use two modules for a full bridge. These devices are full-spec tested units that normally cost well over $1500 each! ($2000 for the FF1200R17KE3) We have a limited amount obtained from an inventory buyout. They can be used for ultra-large TESLA coils, capacitor discharge pulsers, infrasonic ground shakers, segmented rail and coil guns, motor control, power control and many other high-powered applications.

FF1200R17KE3 - High Power IGBT 1200A 1700V ... Call for Pricing

FF600R12KE3 - High Power IGBT 600A 1200V ... Call for Pricing

Siemens IGBT 300A 1200V With diode.
Use 2 pieces in a half or 4 in a full bridge for a spectacular DRSST Solid State Tesla Coil
vacuum tube

Lower power Siemens 300A 1200V single switch. See our FF1200R17KE3 for a more powerful dual switch IGBT.

Free Spec Sheet for BSM200GA120DN12 (note that we sell the BSM300)

BSM300GA120DN12 - High Power IGBT 300A 1200V ... Call for Pricing

60A 600V Semiconductor FET.
Great for medium-power DRSST Solid State Tesla Coils
vacuum tube

60A 600V

Includes mounting hardware.

A good replacement for the discontinued Fairchild HGT1N40N60A4D semiconductor FET. We use 4 of these in our QUASAR60 solid state tesla coil.

IXGN60N60C2D1 - High Power IGBT 300A 1200V ... $32.95