Quick verdict
If you're shopping for data acquisition recorders and want a real chart recorder without spending a lot, the Kipp & Zonen BD 41 is a compelling option at USD 45.00. The unit powers on and button presses produce movement, but it is sold untested and does not include a power cord. That makes it a project instrument rather than a ready-to-run purchase.
Who it suits
This BD 41 is for someone who enjoys restoring or troubleshooting older test equipment. It's also a good fit for a hobbyist, student, or lab person who already owns a compatible power supply and wants a visual chart recorder for experiments. Because multiple quantities are available and each unit may have different markings, the physical appearance you receive can vary, so it helps if you're flexible about cosmetic condition.
Kipp & Zonen BD 41 Chart Recorder
This used Kipp & Zonen BD 41 chart recorder is offered at USD 45.00. It turns on, and different buttons cause movement inside the unit. The catch is that the recorder does not ship with a power cord, and the condition is described as powers on/untested. You're getting basic functional responsiveness at a low price, but not a validated chart-recording performance.
What stands out
The strongest point from the listed details is the entry price. $45 is a low cost for a dedicated data acquisition recorder. The fact that the front-panel controls respond when pressed is reassuring: it suggests the basic movement mechanism is alive. With multiple units to choose from, you may also have some flexibility if markings matter to you, though every unit shares the same no-power-cord and untested status.
Meaningful trade-offs
The biggest trade-off is the missing power cord. You'll need to supply one, which means checking the correct voltage and connector for this exact model. You also have to accept the untested nature: there is no assurance about recording accuracy, pen alignment, or internal condition beyond the button movement. Since each unit may have different markings, your unit may look different from what is described, and that variation is part of the risk.
Bottom line
The Kipp & Zonen BD 41 is worth considering if you want an affordable vintage data acquisition recorder and are comfortable working with used gear. At USD 45.00, the price leaves reasonable room for the extra cost of a power cord and some basic inspection. If you need a fully certified, plug-and-play chart recorder, this is probably not the one. But for a hands-on project recorder, the BD 41 offers a legitimate starting point.
