resistor multiple values

[exxos]

HI all,

Im trying to work out a resistor bank using DIL switches. Now I need a range
such as 50k,100k,150k,200k and so on upto 1meg (50k steps) Now with 20 DIL
switches I could select it like one of 20 and use 20 different resistor
values on each switch, such as switch 1 is 50k, switch 2 is 100k, etc...
though it got me thinking that could I do the same job with just 8 switches
and just use maybe 2 switches on at the same time to get the same values.

It would be easy to start with since 50k could be got with 2 100k resistors
(SW1 & SW2) maybe switch 3 could be 200k, so SW2 and SW3 would give me like
150K ? I dont know , my math aint to great, maybe someone can think of a
easier way to do this or work it out ?

thanks,
Chris

 

[John Miller]

Im trying to work out a resistor bank using DIL switches. Now I need a
range
such as 50k,100k,150k,200k and so on upto 1meg (50k steps) Now with 20
DIL switches I could select it like one of 20 and use 20 different
resistor values on each switch, such as switch 1 is 50k, switch 2 is 100k,
etc... though it got me thinking that could I do the same job with just 8
switches and just use maybe 2 switches on at the same time to get the same
values.

It would be easy to start with since 50k could be got with 2 100k
resistors (SW1 & SW2) maybe switch 3 could be 200k, so SW2 and SW3 would
give me like 150K ? I dont know , my math aint to great, maybe someone can
think of a easier way to do this or work it out ?

Five switches:

50K
100K
200K
400K
800K

and you can select any value between 50K and 1,550K (1.550M) in 50K steps.

--
John Miller
Email address: domain, n4vu.com; username, jsm

Every country has the government it deserves.
-- Joseph De Maistre

 

[exxos]

Five switches:

50K
100K
200K
400K
800K

and you can select any value between 50K and 1,550K (1.550M) in 50K steps.

I have been thinking in parallel for a row of switches. I assume this is
series connection, which I guess could be possible though I dont see how to
link such a arrangement.

chris

 

[dirk]

Five switches:

50K
100K
200K
400K
800K

and you can select any value between 50K and 1,550K (1.550M) in 50K steps.

That would be between 0 and 1550K in 50k steps (all switches closed for 0)

 

[Joe Soap]

Wire all the switches in series and then solder the resistors across the
switch contacts, viola.

More like a trombone than a viola...

 

[John Fields]

More like a trombone than a viola...

 

[John Miller]

A trombone is more like a pot.

Heh...now that you mention it...

....and a valved instrument (for the benefit of those who always wondered how
three valves can produce so many notes) has valves that lower the pitch
(lengthen the tubing) by different amounts, which can be combined, just
like the resistors we're discussing:

1st valve:      whole step
2nd valve:      half step
3rd valve:      minor third

and in combination,

1-2:    minor third
2-3:    major third
1-3:    fourth
1-2-3:  augmented fourth/diminished fifth

John Miller
Email address: domain, n4vu.com; username, jsm

My favorite sandwich is peanut butter, baloney, cheddar cheese, lettuce
and mayonnaise on toasted bread with catsup on the side.
                -Senator Hubert Humphrey

 

[exxos]

Wire all the switches in series and then solder the resistors across the
switch contacts, viola. When a switch is closed, it's resistance is
zero, when it is open, it's resistance is the value of the resistor
across the contacts.

ahhhh, the Euro has dropped! Never thought about doing it that way, thanks!

I also noticed this thread has drifted off topic after only 2 posts ;-)

Cheers,
Chris