The below image is from a service manual for a mobile radio. Note the small symbols that appear to be four triangles, point to point. I've searched far and wide and cannot identify that symbol. I have a nagging feeling that I've seen something like it in hydraulics, but never in an electronics diagram. I know that my radio doesn't have a bunch of stars of David printed inside it, so what could this symbol be?

Some of them have a line through the middle, others don't. Compare for example the ones near the labels "mic int" and "mic ext". Does this represent something, or is it a typo?

circuit diagram

  • \$\begingroup\$ I've looked at all the obvious stuff...protection diodes...buffers...can't find anything that matches these little symbols. \$\endgroup\$
    – Dan
    Oct 18 '13 at 16:35
  • 4
    \$\begingroup\$ Maybe an adaptation of a transmission gate. \$\endgroup\$
    – Dean
    Oct 18 '13 at 16:37
  • 1
    \$\begingroup\$ The ones that have a line through them could be a simple editing/schematic mistake. Don't know what the symbol means though. \$\endgroup\$
    – Passerby
    Oct 18 '13 at 16:37

It looks like it is a transmission gate. Although typically a transmission gate is made up of 4 pins and looks like(made with CMOS):
Transmission Gate

  • \$\begingroup\$ If it's a transmission gate, then where are the control signals? \$\endgroup\$ Oct 18 '13 at 17:58
  • \$\begingroup\$ The schematic is at a block-level. It is either a transmission gate or an interconnect. \$\endgroup\$
    – HL-SDK
    Oct 18 '13 at 18:23
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    \$\begingroup\$ Yes, block level schematics have different rules. I think it is a message from the schematic author; "there's this signal that goes from here to here, but there's transmission stuff that happens along the way, like level shifting, AC coupling, etc, and you can find more detail on the low level schematic." \$\endgroup\$ Oct 18 '13 at 21:57

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