[rcgrant]

The Szekeres schematic calls for a 5W metal film resistor. I suspect no such thing actually exists, so what should I use here? Metal film resistors with lower power ratings in parallel? Wirewound resistors?

 

[Daroid]

Metal Oxide / MOX is IMO a good subsitute for metal film for higher power requirements.

I would guess 5 1W compliant resistors in parallel will work too, but I'm unsure at what happens if just one resistor is slightly lower in resistance (with-in specs) and just how much hotter it will run than the other resistors.

 

[Aye75]

Try kiwame 5w carbon resistors

 

[rcgrant]

Thanks--I found a metal oxide resistor with the right specifications.

Where are the Kiwame resistors available, besides Parts Connexion? They're more expensive than what I'm looking for now but I'll keep them in mind for future projects.

 

[Mpemba Effect]

I used these for my first szekeres. My second build uses an LM317 regulator (Tomo's CCS) which is actually cheaper to build.

 

[Tomo]

Hi,

Wow wee, those resistors are nice, Mpemba Effect. Me wanna.

Wirewounds are perfectly fine. I used silicon filled one. I tried Radio Shack one ... Ceramic type. They are both pretty good.

Non-Inductive wirewounds are also fine. Only problem is that they cost lots. Quality improvement is pretty subtle ... Might not worth that much ...

Just for notes, I strongly believe you will probably need the resistor rated around 10W. My 5W Silicon filled WWs are pretty hot. (Can't dissipate enough heat, methink.) I used to use 25W METAL CLAD WW which was much less burning hot.

Tomo

P.S. I used to use Szekeres amp for my foot warmer.

 

[Dreamslacker]

Quote:

Originally Posted by rcgrant Thanks--I found a metal oxide resistor with the right specifications. Where are the Kiwame resistors available, besides Parts Connexion? They're more expensive than what I'm looking for now but I'll keep them in mind for future projects.

If you insist on using resistors then nice ones are power film resistors like the Caddock MP series resistors that can mount onto To-220 heatsinks. These are available from Percy Audio as well.
Also, Percy Audio has 50W 1% resistors. They're about the same price but can handle much higher power if heatsinked properly. These resistors can be bolted to the case instead of heatsinks for heat dissipation.