Using the QA451 with External Loads

Feel free to post comments or questions on the blog post linked here:

I would think you could use a series-parallel network of modest resistors to get over 1KW continuous dissipation. You would still the the tank of water.

I got some of these to try: https://www.ebay.com/itm/100W-Shell-Power-Aluminum-Housed-Case-Wirewound-Resistor-1-2-4-6-8-10-Ohm/174486964122?hash=item28a03bc79a:g:mnoAAOSw3WZfjovt less than n$3 for 100W (when heat sunk) I checked them. Essentially non-inductive. Less inductance that 3’ of zip cord at 100 KHz. 16 in a series parallel array with some clever patching could get .5 Ohm to 128 Ohm load. I would substitute the QA451 for one of the resistors in the array.

Yes, agree and that style is my preference too.

Given the pigtails on these planer resistors, I’m going to try crimping them together–the same way electricians tie the grounds together in a junction box. I think that will make for very fast assembly of larger arrays. The max 250C rating on the planer resistors is insane, and easy to measure with a point-and-shoot thermometer given the large flat body. There isn’t an IPX rating on these planar, but they are designed for automotive (EVs) and generally if not specified then it means the part is fine to go through an electronics wash (IP67). We’ll see what happens.

Would it be possible to use 2 or more QA451’s in order to increase the power handling capability? Or maybe a separate QA designed box to add on?

Hi @txturbo, I think the simplest and most economical way would be to just add the load resistors externally as outlined in the blog post. That allows you to use ~$25 of resistors and get 2 kW of power handling from the QA451.