Wirewrap board bypass capacitor position problems.

Thread Starter

Constantino Art

Joined Feb 19, 2017
15
I bought an augat wire board for a project, but the bypass capacitor spots are under each IC, so pretty much impossible to connect them there.

However, there are 12 spots for larger, possibly electrolytic capacitors on the sides. Can I use these other spots as bypass capacitors rather than using one ceramic for each IC? Since that's impossible in a usual way, unless I solder them underneath which I really dont want to do.

So the question is, would 12 large capacitors substitute one capacitor per IC on this board? Please look at the photo below:

 

ErnieM

Joined Apr 24, 2011
8,058
The reason there are places for both electrolytic and ceramic capacitors on the board is because you want to use them both.

The electrolytic capacitors provide large slow slugs of current when needed, while the ceramic capacitors fill in for fast short bursts. It's a frequency thing so the belt and suspenders keep your voltage even over all frequencies.

When I was wire wrapping large boards the very first thing I would handle was the power connections, along with the bypass capacitors. A cap at each chip may be overkill but it is also cheap insurance. With a standard ceramic leaded cap (0.1uF typically) I would bend the leads 90 degrees to dress them to the Vcc and Vee pins and solder them into place on the very bottom of the wire wrap pin. For the typical three level wrap pin I suspect is on the bottom of this board you should still be able to get three wraps above the cap lead, certainly two.

Ceramic caps also come an axial leaded bead type of package such as the KEMET C410C104Z5U5TA
These caps sit tighter to the board and don't get in the way of the wrapping wires.

Out of curiosity what wrapping tool will you use?
 

Thread Starter

Constantino Art

Joined Feb 19, 2017
15
The reason there are places for both electrolytic and ceramic capacitors on the board is because you want to use them both.

The electrolytic capacitors provide large slow slugs of current when needed, while the ceramic capacitors fill in for fast short bursts. It's a frequency thing so the belt and suspenders keep your voltage even over all frequencies.

When I was wire wrapping large boards the very first thing I would handle was the power connections, along with the bypass capacitors. A cap at each chip may be overkill but it is also cheap insurance. With a standard ceramic leaded cap (0.1uF typically) I would bend the leads 90 degrees to dress them to the Vcc and Vee pins and solder them into place on the very bottom of the wire wrap pin. For the typical three level wrap pin I suspect is on the bottom of this board you should still be able to get three wraps above the cap lead, certainly two.

Ceramic caps also come an axial leaded bead type of package such as the KEMET C410C104Z5U5TA
These caps sit tighter to the board and don't get in the way of the wrapping wires.

Out of curiosity what wrapping tool will you use?

Hi there. here's a photo of the underside. I think it's a bit of a pain to solder the caps to the pins underneath because they are so clock together. Usually one solder them above, on the sockets, however they are right beneath each IC so it wont fit. I wonder what the developers had in mind when making this board. I can't find a single capacitor that will fit there. My tool is an electric wirewrap gun. I am thinking of buying extra sockets that have space beneath, and put each IC on them so the capacitor fits. This kinda kills the board and costs more but at least its more doable. I would really like to find caps that fit under the IC's



Anyone ?
 
Last edited by a moderator:
Top