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Old 01-03-2022, 07:31 PM   #1
bohaboha
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Default Wirewound Cement Resistor Ceramic explanation

exemoel :10w 20Rj what Rj means? is there anyone who can refer where I can buy 3w + 30kohms cement resistors or higher value for example 40kohms but 3w or what I can I use instead if I can not find
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Old 01-03-2022, 07:56 PM   #2
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Default Re: Wirewound Cement Resistor Ceramic explanation

10W = 10 watts (ceramic block)
20 = ohms
R = Resistor, or the decimal point
j = 5% tolerance.

So no, the 30KΩ resistors won't be the same thing. You could get two 10Ω 5W resistors and stick in series.

Incidentally I don't see much use for a 10W 20KΩ+ resistor these days in modern consumer electronics... You'd need hundreds of volts to dissipate that much power to need a resistor that big and it's indeed just wasting that power. Vacuum tube circuits (including CRTs)!? All bets are off.

Last edited by eccerr0r; 01-03-2022 at 08:03 PM..
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Old 01-05-2022, 08:59 PM   #3
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Default Re: Wirewound Cement Resistor Ceramic explanation

Thank you. but you did not answer my second question if you can suggest something,grateful for all the suggestions that can enrich my searches
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Old 01-06-2022, 10:32 PM   #4
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Default Re: Wirewound Cement Resistor Ceramic explanation

All power resistors will be ceramic. Pretty much everything else has a risk of melting or immolating. I already gave you one option if you can't find the exact value, but they too will be ceramic.
I don't know what sources you have available locally. I'm sure mouser or digikey will have exact replacement units.
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Old 01-06-2022, 11:26 PM   #5
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Default Re: Wirewound Cement Resistor Ceramic explanation

Modern resistors and capacitors follow the EIA standard for values. Example is the EIA-12 is twelve values for the decade, used for parts that have +/-10% tolerance: 100, 120, 150, 180, 220, 270, 330, 390, 470, 560, 680, 820
In that your 30k woud be closest to 27k or 33k, and 40k closest to 39k.

Next is for +/-5% EIA-24 values for the decade: 100, 110, 120, 130, 150, 160, 180, 200, 220, 240, 270, 300, 330, 360, 390, 430, 470, 510, 560, 620, 680, 750, 820, 910.

But it would be still hard to find 40k at several watts, they are not popular and not a standard value really.
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Old 01-08-2022, 05:39 PM   #6
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Default Re: Wirewound Cement Resistor Ceramic explanation

Thanks eccerr0r and redwire the two 10k ohms are not enough and as redwire said it is not easy to find the 40k then what can you have instead?
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Old 01-08-2022, 05:40 PM   #7
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Default Re: Wirewound Cement Resistor Ceramic explanation

Perhaps get 3x 10-KOhms 1-Watt resistors and hook them up in series. Total resistance will be exactly 30 KOhms and the power ratings add up - i.e. 1W+1W+1W = 3W.
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Old 01-08-2022, 06:26 PM   #8
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Default Re: Wirewound Cement Resistor Ceramic explanation

I thought so but where can you find 10k 1w the ones I find are 5w we are talking about Wirewound Cement Resistor of course but it gets clumsy there are no other alternatives?
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Old 01-08-2022, 07:07 PM   #9
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Default Re: Wirewound Cement Resistor Ceramic explanation

for 1w you can use metal oxide / metal film type
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Old 01-08-2022, 07:12 PM   #10
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Default Re: Wirewound Cement Resistor Ceramic explanation

What I need should be 3w and +30k
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Old 01-08-2022, 07:24 PM   #11
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Default Re: Wirewound Cement Resistor Ceramic explanation

Quote:
Originally Posted by bohaboha View Post
What I need should be 3w and +30k
Here:
https://www.mouser.com/c/passive-com...nce=30%20kOhms
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Old 01-08-2022, 08:09 PM   #12
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Default Re: Wirewound Cement Resistor Ceramic explanation

thank you
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