Resistors Less than 100 ohms : Any use?

Started by RandomGlitch, August 02, 2012, 08:17:20 PM

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RandomGlitch

I inherited a whole stack of resistors, and I'm now (inspired by one of chromesphere's videos, I'm sorting them all out logically.

It turns out I have a whole load of low-value resistors, ranging from 1 to 100 ohms. 

I've never seen these used in a pedal circuit, do any designs use these low values? I don't like clutter and having stuff I will never use, so do I keep them or make them into some kind of art or just bin them??

IvIark

Quite a lot of pedals use a low value current limiting resistor in series with the supply, I've seen them as low as 10 ohms and up to 100 ohms in quite a few popular pedals.  Other than that I've rarely seen anything under 100 ohms used.

Cliff Schecht

I use high wattage, low power resistors quite a bit in tube amps. They can be used to drop the supply voltage, the heater voltage, to sense cathode current of the power tubes, to help reduce stress on a power transformer with a tube rectifier, the list goes on. In pedals you really only see small value resistors in the power supply circuits. I use a lot of sub-Ohm values for the current sensing resistor in power supplies.

PRR

> high wattage, low power resistors

? ? ?

I think your fingers got ahead of yourself.

Dropping heaters and sensing large cathodes, you may use high wattage, low value resistors.

(Though if you own a DMM with mV resolution, you use 1 ohm resistors under cathodes and these do NOT have to be high wattage at all.)
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Mark Hammer

Low-value resistors have plenty of good uses:

  • As mentioned, limiting supply current.  Is your LFO ticking?  Stick a low value resistor between V+ and the V+ pin on the op-amps making up the LFO, and a 10uf cap from that pin to ground.
  • Limiting the lowest point on a control.  Look at the Big Muff "Sustain" control.  Does it shut off completely?  No.  And why would you want it too?  A 100R resistor between the ground side of that pot and ground, means that even when the knob is at 7:00 there is still a little bit of signal left.  There are plenty of similar applications of low-value resistors to pots.
  • I've seen plenty of distortion circuits where low-value resistors were used to "soften" the clipping.  Look at the Pocket Rockit here - http://hammer.ampage.org/files/PocketRockit.PDF - and you'll see such an application.
  • Low-value resistors are often used for "Zobel" networks on the output of low-power headphone-amp chips, like the LM386.

Nasse

Used to have zero ohm resistors, supply is empty, don´t know if they can be found somewhere

Very good for breadboarding and prototyping. There was a debate which was better zero ohm resistor or jumper wire. Quess I could made those myself if I had suitable wire and other stuff
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Cliff Schecht

Quote from: PRR on August 03, 2012, 01:10:46 AM
> high wattage, low power resistors

? ? ?

I think your fingers got ahead of yourself.

Dropping heaters and sensing large cathodes, you may use high wattage, low value resistors.

(Though if you own a DMM with mV resolution, you use 1 ohm resistors under cathodes and these do NOT have to be high wattage at all.)

Yeah you know what I meant :P.

LucifersTrip

always think outside the box

asatbluesboy

I love those 0 ohms. Jumpers make me feel like I'm cheating.
...collectors together and emitter to base? You're such a darling...

ton.

Skreddy

I'm using 10 ohms right now for the high-limit of the fuzz pot in Fuzz Face builds (put it in series with the 20 uf cap).  Depending on the build, a 100 ohm, 47 ohm, 10 ohm, or a jumper is appropriate in this spot.

waltk

Conversely, what about high value resistors? any use?

I have a bunch of old 1/4 watt carbon-comp resistors with values up to 22M.  Never use them for anything.

Seljer

Quote from: waltk on August 03, 2012, 10:17:11 PM
Conversely, what about high value resistors? any use?

I have a bunch of old 1/4 watt carbon-comp resistors with values up to 22M.  Never use them for anything.

Ultra high input impedance pedals
High voltage projects (I mean really high voltage, not tube amps, if you ever decide to play with kilovolt stuff)

amptramp

Quote from: Seljer on August 04, 2012, 05:05:49 AM
Quote from: waltk on August 03, 2012, 10:17:11 PM
Conversely, what about high value resistors? any use?

I have a bunch of old 1/4 watt carbon-comp resistors with values up to 22M.  Never use them for anything.

Ultra high input impedance pedals
High voltage projects (I mean really high voltage, not tube amps, if you ever decide to play with kilovolt stuff)

They can be used to bias diodes into conduction so if you have a rectifier-type frequency doubler, it does not cut out below a diode drop.  Most resistors have an upper voltage limit, so if I get a resistor over 10 megohms, I usually get it in a 1-watt size at least, so I can play with kilovolt stuff.

Pyr0

Quote from: RandomGlitch on August 02, 2012, 08:17:20 PM
I've never seen these used in a pedal circuit, do any designs use these low values? I don't like clutter and having stuff I will never use, so do I keep them or make them into some kind of art or just bin them??

No, they are just absolutely useless, get rid of the clutter and post them to me  ;D

marmora

I often use 10 ohm (or something similar) as a dummy load on the output jack of circuit bent toys.

chromesphere

Quote from: RandomGlitch on August 02, 2012, 08:17:20 PM
I inherited a whole stack of resistors, and I'm now (inspired by one of chromesphere's videos, I'm sorting them all out logically.

Funny you say that.  On the weekend one the draws got stuck, a pot was jamming it and i had a temper tantrum while trying to 'forcefully' pull it out smashed it to bits :)

Those low value resistors arent used as much as 100+ ohm resistors from what ive seen but they come up occasionally.  I'd lump them all in a bag together for the odd occasion you need one.

Paul
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RandomGlitch

Yes that's what I thought I'd do. 

Smashed it? Ha, you seemed like a mild-mannered fellow before!  ;)

Think you need bigger drawers. 

chromesphere

#17
Quote from: RandomGlitch on August 05, 2012, 11:19:59 PM
Think you need bigger drawers.  

Ill assume by 'drawers' you mean underpants so thanks for the compliment :)

Smashed it then throw it across the room actually lol my inner guitarist breaks free every now and then. I was having 'one of those' builds and lost my temper.

Seriously need another cabinet though...with bigger draws...

Edit: For all the hardware...its always the bloody hardware that gets stuck (jacks, switches, and even pots).  Makes searching a time consuming process.
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