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Well, since I'm working with surface-mount and trying to keep things as small as possible (and dealing with multiple outputs) I'd more likely go for an IC to power-up the microcontroller outputs rather than do each one individually with a transistor... (Surface mount components are really tiny... The ICs are hard to handle, and individual discrete components like transistors, resistors, or LEDs are just crazy...)

There are several problems I'm trying to work out. The first problem is that I've got basically one place in my model to put in a circuit board, and it's got to be small. (Though it is possible I could come up with an alternate location... I'm investigating that possibility, as well... But the location I'm using now is great 'cause it's accessible and it's very central. The second problem is that I've come up with one design for this board already - it's small enough for the space but there's no room for more components. So to add components I've got to rethink my design a bit. Finally, there's the problem of running wires in this model. It's a humanoid robot model, and the joints have got to be able to move even with the wires in there. And any place wires bridge a joint, I've got to be able to replace the wires if they break later on. I've already got five wires running through the knee joint, for instance (two data, two power, plus one coming down from the microcontroller for lights) - adding more wires there is not an option. This is one of the attractive things about going to higher voltage: I can power more LEDs on the same amount of current if I've got higher voltage, and I'd only have to add a few components to do it. To increase the I/O lines to a higher supply of current at the same voltage may not be so simple. (It all depends on how much current my output amplifier thing can sink...) I can reclaim some board space by making the external connections surface-mount instead of through-hole, and so on - but if I have to add on too many additional components, I'll wind up having to add a second board.

The whole thing is further complicated by the fact that all these decisions have to be interconnected. If I decide to change the supply voltage, for instance, I've got to include that change into the design of other parts of the model. I can't design LED circuits for 6V, seal them up inside model parts, and then later decide to use 12V. (Well, I could, but it could get complicated...) So while there's model work I'm hoping to move forward with even though the microcontroller board isn't ready, that's complicated by the fact that I need it to be compatible with whatever solution I come up with later on.

<blockquote data-quote="tetsujin" data-source="post: 3013" data-attributes="member: 240">Well, since I&#039;m working with surface-mount and trying to keep things as small as possible (and dealing with multiple outputs) I&#039;d more likely go for an IC to power-up the microcontroller outputs rather than do each one individually with a transistor...&nbsp; (Surface mount components are really tiny...&nbsp; The ICs are hard to handle, and individual discrete components like transistors, resistors, or LEDs are just crazy...)There are several problems I&#039;m trying to work out.&nbsp; The first problem is that I&#039;ve got basically one place in my model to put in a circuit board, and it&#039;s got to be small.&nbsp; (Though it is possible I could come up with an alternate location...&nbsp; I&#039;m investigating that possibility, as well...&nbsp; But the location I&#039;m using now is great &#039;cause it&#039;s accessible and it&#039;s very central.&nbsp; The second problem is that I&#039;ve come up with one design for this board already - it&#039;s small enough for the space but there&#039;s no room for more components.&nbsp; So to add components I&#039;ve got to rethink my design a bit.&nbsp; Finally, there&#039;s the problem of running wires in this model.&nbsp; It&#039;s a humanoid robot model, and the joints have got to be able to move even with the wires in there.&nbsp; And any place wires bridge a joint, I&#039;ve got to be able to replace the wires if they break later on.&nbsp; I&#039;ve already got five wires running through the knee joint, for instance (two data, two power, plus one coming down from the microcontroller for lights) - adding more wires there is not an option.&nbsp; This is one of the attractive things about going to higher voltage: I can power more LEDs on the same amount of current if I&#039;ve got higher voltage, and I&#039;d only have to add a few components to do it.&nbsp; To increase the I/O lines to a higher supply of current at the same voltage may not be so simple.&nbsp; (It all depends on how much current my output amplifier thing can sink...)&nbsp; I can reclaim some board space by making the external connections surface-mount instead of through-hole, and so on - but if I have to add on too many additional components, I&#039;ll wind up having to add a second board.The whole thing is further complicated by the fact that all these decisions have to be interconnected.&nbsp; If I decide to change the supply voltage, for instance, I&#039;ve got to include that change into the design of other parts of the model.&nbsp; I can&#039;t design LED circuits for 6V, seal them up inside model parts, and then later decide to use 12V.&nbsp; (Well, I could, but it could get complicated...)&nbsp; So while there&#039;s model work I&#039;m hoping to move forward with even though the microcontroller board isn&#039;t ready, that&#039;s complicated by the fact that I need it to be compatible with whatever solution I come up with later on.</blockquote>

[QUOTE="tetsujin, post: 3013, member: 240"] Well, since I'm working with surface-mount and trying to keep things as small as possible (and dealing with multiple outputs) I'd more likely go for an IC to power-up the microcontroller outputs rather than do each one individually with a transistor... (Surface mount components are really tiny... The ICs are hard to handle, and individual discrete components like transistors, resistors, or LEDs are just crazy...) There are several problems I'm trying to work out. The first problem is that I've got basically one place in my model to put in a circuit board, and it's got to be small. (Though it is possible I could come up with an alternate location... I'm investigating that possibility, as well... But the location I'm using now is great 'cause it's accessible and it's very central. The second problem is that I've come up with one design for this board already - it's small enough for the space but there's no room for more components. So to add components I've got to rethink my design a bit. Finally, there's the problem of running wires in this model. It's a humanoid robot model, and the joints have got to be able to move even with the wires in there. And any place wires bridge a joint, I've got to be able to replace the wires if they break later on. I've already got five wires running through the knee joint, for instance (two data, two power, plus one coming down from the microcontroller for lights) - adding more wires there is not an option. This is one of the attractive things about going to higher voltage: I can power more LEDs on the same amount of current if I've got higher voltage, and I'd only have to add a few components to do it. To increase the I/O lines to a higher supply of current at the same voltage may not be so simple. (It all depends on how much current my output amplifier thing can sink...) I can reclaim some board space by making the external connections surface-mount instead of through-hole, and so on - but if I have to add on too many additional components, I'll wind up having to add a second board. The whole thing is further complicated by the fact that all these decisions have to be interconnected. If I decide to change the supply voltage, for instance, I've got to include that change into the design of other parts of the model. I can't design LED circuits for 6V, seal them up inside model parts, and then later decide to use 12V. (Well, I could, but it could get complicated...) So while there's model work I'm hoping to move forward with even though the microcontroller board isn't ready, that's complicated by the fact that I need it to be compatible with whatever solution I come up with later on. [/QUOTE]

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