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What happend to 320K resistors ?
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ogden:

--- Quote from: srb1954 on February 20, 2021, 08:40:35 am ---SMD may have some advantages for non-critical applications but it has some severe disadvantages in high power circuitry:

* The power handling capability for pulse loads for most types of SMD resistors is abysmal
* The ability of SMD resistors to withstand high peak voltages is poor
* The ability to withstand thermal cycling stress with pulsed loads is poor, especially when using lead-free solder
* If the application requires power dissipations more than several watts the heating of the PCB material and surrounding components becomes excessive with SMD parts
If any of the above situations applies the best option is often to stick with leaded parts.

--- End quote ---

Limiting factor is PCB heat handling properties, not SMT resisors as such. 35W SMT resistor for example: RHFH4Q050R0FE. If you need smaller heater on your PCB, then consider Vishay RCP series or similar.

Low voltage rating of small SMT resistors is due to their (surprise surprise!) size. Simple solution - put multiple resistors in series or use higher voltage rating SMT resistors, usually both. Open parametric search of your parts distributor and see for yourself - plenty of choices.
ogden:

--- Quote from: Siwastaja on February 20, 2021, 08:58:11 am ---It's not a choice whether to build the entire thing in THT or SMT, that would be stupid.

--- End quote ---

Stupid would be to not try to build entire thing using SMT only. To state obvious: THT is added cost. Here I talk about electronics manufacturing in general.
Siwastaja:
Yes, I always try to default to full-SMT design whenever possible. The opposite, trying to default to THT, is becoming a masochistic act I think.

At some point I realized that TH parts isn't as much extra cost you could think it is. If you do a proto batch of 10, just solder them yourself, takes an hour. If you do 100, let the Chinese CM solder them for you. What I have seen, the quality is OK.

So I don't feel bad using TH parts when there is an advantage, for example the large caps, bulky connectors and high power resistors, high voltage parts. And TH pin header takes less board area than SMD pin header.

BTW regarding resistors that dissipate a lot, sometimes this is a sign of bad circuit design. Always when dissipating power, ask the fundamental question, why do you need to dissipate? Sometimes you can just make the circuit more efficient, save space, assembly cost, and energy. For example, instead of dissipating 5W in a current measurement resistor, use a higher gain, lower offset amplifier and dissipate only 1W. Or instead of "regulating" current by CV supply + series resistor, design a CC supply.
langwadt:

--- Quote from: wraper on February 20, 2021, 03:33:08 am ---
--- Quote from: coppercone2 on February 20, 2021, 03:27:22 am ---1/4 watt

you want a 1/4 watt smd you get 1206 minimum , depending on what your customers believe

--- End quote ---
You can buy 0.3W in 0805. In 1206 you can get up to 1W.  And you don't need 1/4W in 99% of cases, 1/16W or 1/8W is more than enough usually. Just because small TH resistors usually come with 1/4W rating does not mean you actually need it.

--- End quote ---

they don't exactly give them away but digikey has plenty 0.4W, 0.5W and some 1.5W 0603

ebastler:

--- Quote from: Jan Audio on February 19, 2021, 03:59:29 pm ---I dont have anything SMD, searching for normal axial resistors.
Soldering more resistors is not the plan, i still have some 320K resistors, i want more.

--- End quote ---

Bit stubborn, are we?  ::)
I guess you have two plausible options:

(a) Take one of the various recommendations given in this thread, or
(b) keep searching for 320k resistors, quietly please.

Digging in your heels here in the forum until someone makes 320k resistors for you is not one of them, I'm afraid.
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