The nicest way to do it is to use a 9 volt battery connector like this and then hold the wire against the terminals (or if you're fancy make a dummy AA battery and put the 9 volt wires where the AA contacts would be, then you can leave it in a AA (and C cell if you wedge it right) battery slot without having to hold it)
![[Image: 9-Volt-Battery-Snap-Connector-578.jpg]](https://i.postimg.cc/CBgJKPR8/9-Volt-Battery-Snap-Connector-578.jpg)
Or, the cheaper don't have to try to find a 9 volt battery clip method is to take two bare metal paper clips and wrap them around the battery terminals, being careful not to short them together, then touch them against the engine's contacts. The slightly easier to control version is to wrap some spare lengths of wire if you have them around each battery terminal and then hold the other ends against the engine's contacts. The wire ought to be more flexable and easier to position how you want it, and you can make a fake AA to hold them like with the battery clip but you can't replace the 9 volt without untwisting the wires from both terminals.
Or, the cheaper don't have to try to find a 9 volt battery clip method is to take two bare metal paper clips and wrap them around the battery terminals, being careful not to short them together, then touch them against the engine's contacts. The slightly easier to control version is to wrap some spare lengths of wire if you have them around each battery terminal and then hold the other ends against the engine's contacts. The wire ought to be more flexable and easier to position how you want it, and you can make a fake AA to hold them like with the battery clip but you can't replace the 9 volt without untwisting the wires from both terminals.
I have a website where I have been writing about and photographing many of the sets and pieces that I find interesting.
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