Dr.Boogie Build Questions.

[steveyraff]

Ok cool - great info guys - I'll try both. I already have 5k linear pots and 5.1k ohm resistors, and I also have 10k Pots as Joker suggests. I look forward to trying all of these and checking out the differences.

Great help guys, Cheers.

[greaser_au]

Speaking of tolerances, I wonder if resistor manufacturers just measure their product and when it passes the 1% it gets painted blue, else that brownish color.

More likely it would just get shunted into the bin for the next preferred value, as it would likely be within 1% of that!!!! 

david

[Kipper4]

Don't buy any 2K pots....

Take a 5K linear pot (5KB) and put a 5.1K resistor between Lug 1 and Lug3...... VIOLA.... its now a 2.5KB pot 

I've done this with all of my Boogie builds. Works great.

You might even be able to use a 4.7K resistor but it will be a little more "off" than the 5.1K

^me too Stevie

[vigilante397]

I recently finished a Dr. Boogie build using the fabulous Madbean's "Chunk Chunk" layout, and it calls for a 5k pot instead of the 2.5k.

[Govmnt_Lacky]

I recently finished a Dr. Boogie build using the fabulous Madbean's "Chunk Chunk" layout, and it calls for a 5k pot instead of the 2.5k.

Brian incorporated the parallel 5K1 resistor into the PCB 

[vigilante397]

Brian incorporated the parallel 5K1 resistor into the PCB  

Just took a look at the PCB and you are absolutely right There you have it then

[steveyraff]

Yea I'm waiting for all the parts to arrive for the build still, but I'm going to go for the 5k pot with resistor I think. Good to know how to do this for future reference too!

Cheers dudes.

[Kipper4]

Google up parallel and series resistors Stevie.
comes in real handy some times when you buy a kit bag and dont have the exact value, plus bear in mind the 10% thing.
then do the same for capacitors and see what you find.

[steveyraff]

Google up parallel and series resistors Stevie.
comes in real handy some times when you buy a kit bag and dont have the exact value, plus bear in mind the 10% thing.
then do the same for capacitors and see what you find.

Ok cool - very useful. Thanks Kipper!

[Mike2E]

stevieraff, I have an LCR meter and access to standards in a lab. Resistance standards are spec'd to ppm whist caps only to 0.01% or so. When measuring low values ( below) leg length and spacing affect the value read. The pcb you mount them in has capacitance, which with RF can create real challenges. As mentioned 10% won't be a problem. Electrolytics are typically 20% but can be +100 and -50% of marked values.
I have heard that if you run them near the rated voltage they will get closer to nominal value but when run at much lower they increase value. I have seen this but could not prove it

[steveyraff]

Hey guys,

Almost finished building this. Just a quick question about my last components I'm about to solder in.

If you refer to the build layout in my first post, the two 220nf caps at the far right of the layout... I have little bead Tantalum 35v 220nf caps to put in there. However there appears to be one leg shorter than the other on them, suggestion to me they are actually electrolytic and have a polarity? The layout doesn't used polarised caps - can anyone tell me what orientation I need to solder them in?

Many thanks!

[Kipper4]

those tatulums are polarised. if you look closely often theres a + sign on the side with the longest leg.
The layout asks for non polar but since your going with Keens second law.
I suggest the side with the most voltage would be coming from the 4k7 and thats where id put the long + side legs. (so plus side pointing up )
Im prepared to be corrected though.
Rich

[steveyraff]

those tatulums are polarised. if you look closely often theres a + sign on the side with the longest leg.
The layout asks for non polar but since your going with Keens second law.
I suggest the side with the most voltage would be coming from the 4k7 and thats where id put the long + side legs. (so plus side pointing up )
Im prepared to be corrected though.
Rich

It's my own fault for not studying the layout carefully before ordering my parts in, Kipper. I'll try the orientation you suggested. If this orientation is wrong, will it just not work at all, or is there any way damage can be done?

[Kipper4]

I'd have thought the worse thing that could happen is the caps blow up.
or the filter (B M T tone control wont work)
you will need to tune the circuit to get some good sounds out of it first. Its worth spnding some time on that to make it sound awesome.
Google up others DR Boo voltages because IIRC they were significantly lower than I expected on some tranistors.
Expect some feedback on the amp when your tuning it too IIRC. especially outside the enclosure.

[steveyraff]

I'm scared. 

[Kipper4]

Anybody see a problem with my suggestions.

[stallik]

I'd have thought the worse thing that could happen is the caps blow up.

Doubt it, maybe not work, fail etc but blow up sound like a bit of an explosion?... Hey! Maybe that's how you make a burst box
Seriously, I've been forced to use a polarised from time to time and, as you say, provided you orient it right, it's usually OK

[Tony Forestiere]

Before you solder the caps, apply power and measure voltage at each point of the cap pads from ground. Orient the + leg at the more positive of the two points. (Of course, I don't know anything  ).

[J0K3RX]

I wouldn't go with the "plus side pointing up" method myself.. You never know, one mans up is another mans down when laying out these boards. Not like anything bad is gonna happen besides a little smoke at the most but save yourself a component or two and figure out the correct orientation either by looking at the board and schematic or use your meter. Or, do what I do and rip apart one of your kids toys (preferably one the they no longer play with if possible) and pillage it for the part you need ha ha..

[vigilante397]

Madbean's documentation includes a schematic, so you could check that out. Or a method that works with many circuits (I've always nervous to say anything works with ALL circuits) is to put it all together with the components you have and fire it up, then take your meter to the pads for the cap and check voltages. Hgiher voltage = positive lead (longer) of the cap goes there.