Guess my Value...

[talrek]

Hi,
here is a resistor, i tried to find the value but i can't.
Colors seem to be : red red black gold white

But when i search for colors value, i can't find with white in fifth position...
Also when i use a multimeter the value is in MOhms, but it changes between 5 and 2,2 MOhms...

[Bryce]

I think the mistake is in the sentence "here is a resistor".... That looks like an inductor, not a resistor.

Bryce.

[talrek]

I think the mistake is in the sentence "here is a resistor".... That looks like an inductor, not a resistor.

Bryce.

thank you, this is a part of a Dk'Tronics Mouse interface. I don't understand its purpose... I mean why use an inductor ?

Also my problem is the value... I see 5 bands : red,red,black,gold and white.
but white in first position neither...

It is why i supposed it was a resistor and not an inductor, i don't know of any 5 bands inductor like this. Usual 5 bands inductors have always a wider first silver band...

[reidrac]

It looks like a resistor to me , 22 ohms, +- 5%.

Could it be a problem wit the multimeter or the probes? Can you verify it can read another 22 ohms resistor?

[talrek]

It looks like a resistor to me , 22 ohms, +- 5%.

Could it be a problem wit the multimeter or the probes? Can you verify it can read another 22 ohms resistor?

Hi, my Multimeter (Ohmeter) works well with other résistors no variable results... I thought about a faulty resistor, but i still don't get the value...

[reidrac]

My experience with faulty resistors is that they just burn and no electricity can pass through them; but it could be that is damaged and it may just have more or less resistance.

To be honest, given how cheap they are, if I'm not sure... I just bin it and get another one that behaves correctly

[Bryce]

Hi, my Multimeter (Ohmeter) works well with other résistors no variable results... I thought about a faulty resistor, but i still don't get the value...

Can you post a photo of the circuit board so that I can see where it was?

Bryce.

[talrek]

Can you post a photo of the circuit board so that I can see where it was?

Bryce.

Ok thanks it gave me an idea and i found it was a capacitor !!! 
You can see on the pictures attached that it is connected to pin 1 and 3 of a TC4047BP and is coupled with a resistor and pin 2 of the same IC.

So i searched the datasheet, and tada !!! saw it was a capacitor 
If i read the colors correctly it is a 22pF capacitor .

So BTW if someone could modify the CPCwiki page for the Dk'tronics mouse interface, it is written there are 3 résistors (correct) and 1 Capacitor (i guess the eletrolytic one, miss the ceramic one )

[attachimg=1]
[attachimg=2]

[Bryce]

Glad you got it sorted. The base colour is what made me suspect that it wasn't a resistor. Back then they made inductors and capacitors in very resistor-looking cases, the only giveaway is that they usually used that funny green or mustard colour instead of the usual beige for carbon resistors or blue for metal-film resistors. The dodgy resistor reading you were getting was the capacitor charging and discharging from your meter.

Bryce.

[talrek]

Glad you got it sorted. The base colour is what made me suspect that it wasn't a resistor. Back then they made inductors and capacitors in very resistor-looking cases, the only giveaway is that they usually used that funny green or mustard colour instead of the usual beige for carbon resistors or blue for metal-film resistors. The dodgy resistor reading you were getting was the capacitor charging and discharging from your meter.

Bryce.

Yes and to add to all this confusion, on the internet you have example of green resistor which is categorized as metal-film resistor.
But to solve this problem, i'll replace the capacitor with a "modern" one on the interface ;-)

[reidrac]

That packaging for a cap is awful

[Bryce]

That packaging for a cap is awful

They were a bit confusing if you didn't have a schematic, but they were actually quite robust and acurate parts. You still see them alot on old amusment and arcade PCBs. There were also glass capacitors that looked like germanium diodes!

Bryce.

[talrek]

They were a bit confusing if you didn't have a schematic, but they were actually quite robust and acurate parts. You still see them alot on old amusment and arcade PCBs. There were also glass capacitors that looked like germanium diodes!

Bryce.

Ahhh electrolytic paleolithic components 

[Ygdrazil]

I updated the wiki page okay? 

searched the datasheet, and tada !!! saw it was a capacitor 
If i read the colors correctly it is a 22pF capacitor .

So BTW if someone could modify the CPCwiki page for the Dk'tronics mouse interface, it is written there are 3 résistors (correct) and 1 Capacitor (i guess the eletrolytic one, miss the ceramic one )

[Bryce]

This is what the old glass capacitors looked like, in case you ever come across them:

http://www.mrdwab.com/john/Whatsthis.jpg

Bryce.

[talrek]

I updated the wiki page okay? 

Well, in fact there are 2 caps :
- Electrolytic = 1uF
- Ceramic = 22pF

[talrek]

This is what the old glass capacitors looked like, in case you ever come across them:

http://www.mrdwab.com/john/Whatsthis.jpg

Bryce.

it looks almost like some diode to me ;-) hopefully the value is written on it 

[Bryce]

it looks almost like some diode to me ;-) hopefully the value is written on it 

No, but the diodes only have the red stripe at one end, capacitors at both ends. I think they only ever went to 100nf anyway.

Bryce.