Prototyping and resistors question

[ViolenceOnTheRadio]

What would be a more reliable means to test different resistances for placement in a circuit when prototyping.
A few different value pots I can just turn until I like what I hear then test with a meter for resistor selection or, a couple 1 pole 12 position switches with ascending values of resistors wired to them and then cycle through the values that way.

About to build a couple for caps, not sure how I should go about creating a means to test various resistances.

[petemoore]

  Either way that gets the resistances you need, sweep or selections you want.
  Pot is generally easier to start with though.
  About to build a couple for caps, not sure how I should go about creating a means to test various resistances.
  There is no 'pot is to resistor' for a capacitor, adjusting may involve switching values in various ways or putting a resistance [or variable resistor=pot] inline with a capacitor or capacitors [see easy face with input blend mod.
 

[ViolenceOnTheRadio]

......
  There is no 'pot is to resistor' for a capacitor, adjusting may involve switching values in various ways or putting a resistance [or variable resistor=pot] inline with a capacitor or capacitors [see easy face with input blend mod.
 

lol yeah, seems the mention of the 1 pole 12 position switch went right over your head. I'm not quite a newb though man. You wire ascending values to the 12 lugs and cycle through them hence 1 pole, 12 position. I'll do 1 with polypropylene caps, the other with ceramic of equal values. That's 2 switches right there and I couldn't decide on 2 or 4 but times are tough lol. I'll just use a few pots since I have so many then check favored positions with a meter.
I have however made the "variable" cap by wiring a couple to a low resistance pot. Makes a great way to turn the treble of my home brew two band tone stack into a midrange.

Oddly, I for some reason dread the thought of commercial designers adding these simple but clever DIY brew controls which range from the variable cap to clipping character switches, EQ mode switches etc.

[Ronsonic]

You might want to try shopping. These can be expensive but there are bargains to be had and I've scarfed a few. The phrase you are looking for is "decade box" as in capacitor or resistor decade box.  All made up with switches and jacks and professional like. Very pricey for new lab grade stuff, very affordable for flea market and hamfest Heathkit and the occasional Mil surplus score.

[LucifersTrip]

 There is no 'pot is to resistor' for a capacitor
 

...but they are bulky, expensive and only vary over a small range

[studiostud]

what your talking about is pretty much what I built.  I did a little "tweaking unit" for testing various components.  I have a resistance section with two sets of potentiometers (lin and log) that I can sweep through.  I have a capacitance section with a 4-way rotary that selects one of 4 different 12-way rotaries (electro, ceramic, poly low, poly high).  There is a diode section with a 2-side 10-pin DIP switch that allows me to test different diode pairs.  The last section is for trannies.  I have a 3PDT switch with each side connected to a tranny socket so I can A/B test 2 trannies at a time w/o just swapping them out and losing part of my "tone memory".

[ViolenceOnTheRadio]

I actually have a few variable capacitors in trim pot type format. They're generally very low value, pF, and anything in the uF ranges get pretty expensive. I'm also willing to bet they're more or less what some of us implement to make a variable cap by using a low value pot and a couple caps where one is double the value of the other so there is a smooth transition through the value if you bother to slap it on a meter to test the linearity of the transition.

Studiostud my hat goes off to you. You've put together one heck of a prototyping rig and it made me realize my protoboard isn't as useless as I thought. It seems running leads from a console filled with chip sockets, cap and resistor sockets, pots and of course the rotary switches loaded with caps would make prototyping with protoboard much much easier. I have Frankenstein sized hands so when my protoboard came in the mail, which I had ordered what was in the medium to large range, I was in disbelief of what was around the size of a few credit cards
I was expecting something the size of a piece of notebook paper or at least half that! Surely it would make sense for protoboards to be so large considering the amount of lead on passives, the size of most males hands and the manufacturers could simply offer sockets for actives with leads built to compensate.

[studiostud]

yeah.  I hear ya.  my original intention was with each design I did, I would make a PCB first that was all sockets and then I could populate it and swap out individual components with wires to the "tweaker".  But then the brilliant idea dawned on my that I would save a lot of hassle and money (from buying all though inline sockets), if I just picked up a breadboard.  It was a bit of an investment ($40 at a local reputable electronics shop), but it was worth it.  Now I can breadboard up my circuits first and swap out components very easily and with more real estate than I would have on a PCB, I don't have to worry about clipping the leads off the components to keep them from bumping into each other.

For the breadboard, I actually built my own version of the Beavis Board.  Check it out cause you could do the same thing:  http://www.beavisaudio.com/bboard/


Peace.

J

[R.G.]

Google.

"resistance substitution box"

"capacitor substitution box"

[studiostud]

they have them at partsexpress. 

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=320-076%20%20%20%20%20%20%20%20&FTR=resistor%20substitution&CFID=9157878&CFTOKEN=11908273

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=320-076%20%20%20%20%20%20%20%20&FTR=resistor%20substitution&CFID=9157878&CFTOKEN=11908273


that's actually where I got the idea initially.  With these kits though, there were enough limitations with those that I just decided to build my own.  Like with the resistor one, I didn't like that they were rotary switches with set values.  That's why I did mine with pots so I could be more precise with my tweaking.  And with the capacitance, I didn't like that it didn't go lower than 100p or higher than .1uF.  Plus, I'm 100% positive that I made mine for 1/4 the cost. 

[deadastronaut]

yeah they look handy...

@studiostud...yeah pots, it'd be good with a meter display built in it too....very exact!..

but i guess someone sells them already right!.

[studiostud]

that's actually a really good idea!  I might have to look into doing a little LCD display to measure the values.  I could just build in a cheap multimeter, but what's the fun in that.  plus, a multimeter cheap enough to gut and modify probably won't be extremely accurate.  I was thinking maybe building a multi-meter like device using an old calculator display.  I could probably even get an old calculator that's solar powered so I wouldn't have to use a battery!

[deadastronaut]

that's actually a really good idea!  I might have to look into doing a little LCD display to measure the values.  I could just build in a cheap multimeter, but what's the fun in that.  plus, a multimeter cheap enough to gut and modify probably won't be extremely accurate.  I was thinking maybe building a multi-meter like device using an old calculator display.  I could probably even get an old calculator that's solar powered so I wouldn't have to use a battery!

yeah it would be very handy...cool project too...i wouldnt know where to start with lcd's..but it would be a great practical device..

[ViolenceOnTheRadio]

I saw the ones from Parts Express probably over 10 years ago, long before I had gotten into the pedal building and amp modding trade. I then built my first circuit which was a kit from Paia, a tube preamp. My soldering iron was pretty cruddy and I had to send the finished kit in to be worked on lol. But it turned out it was because of their ratty parts. If you tightened the 1/4 jacks so they would actually hold in the panel, the threaded sleeves would just pop out and the ceramic backings would fall off after plugging your cable in a few times. Even their knobs fall apart! The problem was the 1/4 jacks were shorting and my pc assembly had turned out fine.
Fast forward about 5-6 years and that's when I built my first pedal. I decided to build my own resistance and cap boxes on rotaries for prototyping since by my third project I was engineering my own circuits from the ground up but, I never bothered beyond the one I made for resistors. Here I am several years later and figured it was about time since I'm more lucrative in the hobby and seeking to make it one of my trades. I'm also sick of tack soldering polypropylene caps in and out of prototypes which eventually, breaks the leads off rendering them useless and money in the crapper.

$5 for two 12 position rotary switches - Ebay
$4-$5 in ceramic and polypro caps
$4-$5 for a few pots
MUCH cheaper than Parts Express and far more useful since I'll have more logical values and different cap types. I think I'll dismantle that old rotary I put the resistors on and stock it up with 12 electrolytic caps just so all bases are covered.

[LucifersTrip]

$5 for two 12 position rotary switches - Ebay
$4-$5 in ceramic and polypro caps
$4-$5 for a few pots
MUCH cheaper than Parts Express and far more useful since I'll have more logical values and different cap types. I think I'll dismantle that old rotary I put the resistors on and stock it up with 12 electrolytic caps just so all bases are covered.

I just ordered a bunch of rotary switches from Futurlec...they are $1 . I'm sure the pots [.55] and caps are less, too, but the wait isn't.
http://www.futurlec.com/cgi-bin/search/qty_price.cgi?part_no=ROTP1P12

good luck

[ViolenceOnTheRadio]

WoW great link!
Low price on those switches and a very fair price for shipping. I get my polypro caps from effectsconnection for a good price and fair shipping but everything else, I had been ordering from Asia through Taydaelectronics.com which was dirt cheap. Recently though, their shipping cost turned into a system of wallet rape.
I just ordered 22 bucks worth of supplies with shipping and got literally 1/4 what I normally did in the past when spending this much, simply due to their absurd shipping price hike. It was great, you'd spend 20 bucks and get a massive bundle of pots, resistors, caps, diodes etc. and now...it's like buying from the middle man that supplies radioshack!

[.Mike]

...I had been ordering from Asia through Taydaelectronics.com which was dirt cheap. Recently though, their shipping cost turned into a system of wallet rape.

Tayda's shipping prices increase pretty quick if you're ordering pots. They're a lot heavier than most anything else we buy. Can't beat their prices on some items though, like PT2399s.

Futurlec is pretty good, but if you order enough stuff, they automatically bump you up to Fedex shipping. When I first bought my parts stock, Futurlec wanted $55 to ship a $150 order. I had them split it into two separate orders, which still ended up costing me like $30 in shipping. They still sent it Fedex.

Mike

[stringsthings]

lol yeah, seems the mention of the 1 pole 12 position switch went right over your head. I'm not quite a newb though man. You wire ascending values to the 12 lugs and cycle through them hence 1 pole, 12 position....

wow ... thanks for enlightening us with that information .... since you are so knowledgeable, should we bow to your fountain of clever writing?  or am i going "right over your head"?

[trjones1]

Futurlec's rotary switches are good and a great value, but I just want to warn about their toggle switches, which are crap (except for the 3pdt, which is actually very good quality).

[stringsthings]

Futurlec's rotary switches are good and a great value, but I just want to warn about their toggle switches, which are crap (except for the 3pdt, which is actually very good quality).

+1

i have also had trouble with the SPDTs and DPDTs from Futurlec ... it's too bad because their price is so low .... but for me, i'd rather spend a bit more for ease of use and reliability ... maybe they'll get higher qualtiy switches in the future ( crossing fingers ) ...