Cybercow
Well-known member
Many of us have been there. PCB is freshly populated, tested and working great. Now it's time to stuff all that goodness into a prepped enclosure. The drill holes have all been made and pre-fit tested for proper alignment and the guts go in nicely and even the jacks are spot-on with no interferences. Great! But then you go to screw that bottom plate on, only to find a few of the caps are too tall for the bottom plate to rest flat for closure.
Sometimes we can go back in and lay some of those tall caps on their side, or perhaps there is room on the solder-side of the PCB the jockey those tall caps around. And sometimes none of those approaches work. It all depends on the build, the enclosure and the planning in its entirety.
That damned Z-axis! How many times do we overlook the z-axis when planning a build for enclosure fitting? I know I have, and too many times. Sometimes I had to re-order a deeper enclosure, say a 1590N or 125B for the 1590B, or a 125BB for the 1590BB that are shallower.
One day, on whim, I though to order a few different SMD electrolytic caps just see if those could be used. I just ordered a generic SMD electrolytic capacitor kit and when they arrived I noticed they have this small plastic shroud on the bottom. At first I thought: "Bummer!" Then I thought maybe that plastic bottom shroud would come off easily and the flat pins could be straightened to be like regular TTH caps.
The first thing I found out is that those legs on SMD electrolytic caps are aluminum, thin and fragile. Bend 'em too many times and the metal fatigue gets the better of them and they break. So, with a delicate hand I carefully removed the plastic shroud, gently straightened the pins - being careful to bend slowly and only as much as needed. The I set the shroudless SMD electrolytic cap into the holes for the 100µF on the PCB. The SMD legs are perfectly spaced for most electrolytic hole spacing and lo & behold, there is even enough of the SMD legs sticking thru the PCB to bend a bit to hold 'em in place while the PCB is upside-down and ready for soldering. The solder took and the joints looked good. Voila! A solution for large electrolytic caps without resorting to tantalums or searching forever thru complicated search engines to find the right, or even just shorter, electrolytic caps.
Here is a photo I took of a few different 100µF TTH e-Caps and two different SMD e-Caps with their respective specs and measurements. Over the past year or so, I would try different sizes of standard TTH e-Caps available from Mouser just to have some physically on hand to work with and see how well would or would not work in my pedals. It's difficult to source small TTH e-Caps of any real quality, especially for the larger values like 47µF and 100µF. Sometimes they are too tall, or when a shorter one is found, its width is too wide to fit easily next to components around it. The SMD versions will almost always work. Again, depending on the build. YMMV
I built out 20 of the PedalPCB "Proposition" boards using SMD e-Caps, except for the 1µF e-Cap which was small enough on its own. They fit quite nicely into a 1590BB enclosure with height issues.
In summary, for me at least, I find using SMD e-Caps a great alternative for larger TTH e-Caps. SMD e-Cap kits are cheap - about 20 bux for an assortment with 400 caps ranging from 1µF @ 10V to 1000µF @ 16V with higher voltage specs on the 330µF and below. For me, the 100µF @ 35V is the winner for most every need for a 100µF e-Cap.
Sometimes we can go back in and lay some of those tall caps on their side, or perhaps there is room on the solder-side of the PCB the jockey those tall caps around. And sometimes none of those approaches work. It all depends on the build, the enclosure and the planning in its entirety.
That damned Z-axis! How many times do we overlook the z-axis when planning a build for enclosure fitting? I know I have, and too many times. Sometimes I had to re-order a deeper enclosure, say a 1590N or 125B for the 1590B, or a 125BB for the 1590BB that are shallower.
One day, on whim, I though to order a few different SMD electrolytic caps just see if those could be used. I just ordered a generic SMD electrolytic capacitor kit and when they arrived I noticed they have this small plastic shroud on the bottom. At first I thought: "Bummer!" Then I thought maybe that plastic bottom shroud would come off easily and the flat pins could be straightened to be like regular TTH caps.
The first thing I found out is that those legs on SMD electrolytic caps are aluminum, thin and fragile. Bend 'em too many times and the metal fatigue gets the better of them and they break. So, with a delicate hand I carefully removed the plastic shroud, gently straightened the pins - being careful to bend slowly and only as much as needed. The I set the shroudless SMD electrolytic cap into the holes for the 100µF on the PCB. The SMD legs are perfectly spaced for most electrolytic hole spacing and lo & behold, there is even enough of the SMD legs sticking thru the PCB to bend a bit to hold 'em in place while the PCB is upside-down and ready for soldering. The solder took and the joints looked good. Voila! A solution for large electrolytic caps without resorting to tantalums or searching forever thru complicated search engines to find the right, or even just shorter, electrolytic caps.
Here is a photo I took of a few different 100µF TTH e-Caps and two different SMD e-Caps with their respective specs and measurements. Over the past year or so, I would try different sizes of standard TTH e-Caps available from Mouser just to have some physically on hand to work with and see how well would or would not work in my pedals. It's difficult to source small TTH e-Caps of any real quality, especially for the larger values like 47µF and 100µF. Sometimes they are too tall, or when a shorter one is found, its width is too wide to fit easily next to components around it. The SMD versions will almost always work. Again, depending on the build. YMMV
I built out 20 of the PedalPCB "Proposition" boards using SMD e-Caps, except for the 1µF e-Cap which was small enough on its own. They fit quite nicely into a 1590BB enclosure with height issues.
In summary, for me at least, I find using SMD e-Caps a great alternative for larger TTH e-Caps. SMD e-Cap kits are cheap - about 20 bux for an assortment with 400 caps ranging from 1µF @ 10V to 1000µF @ 16V with higher voltage specs on the 330µF and below. For me, the 100µF @ 35V is the winner for most every need for a 100µF e-Cap.
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