Hood Tech manufactures preamps of two types: optical (BV-OP) and eddy current (BV-IND), both shown in Figure 1. Each preamp supports three sensors. Each preamp is about the size of a paper-back book and is powered by its own data cable (no power is required near the device under test.). It should be noted that the preamplifiers are required only when using model 8030 data acquisition console. The preamplifiers are integrated into model 4016C. This is described in more detail below.
1. Eddy Current Preamp (BV-IND)
The Hood Technology Corp. 3-channel eddy current preamplifier has three identical channels, each of which implements preamplification for any Hood Tech eddy current sensor. The preamp is powered by the data console through a 9-pin sub-D cable. Each channel has an easily adjustable gain up to 100X and an optional attenuator for occasions when the input signal is too large. The buffered output can drive cables (up to at least 150m) without signal degradation. It can also act as a signal repeater for longer spans of cabling to the data console.
2. Optical Preamp (BV-OP)
The Hood Technology Corp. 3-channel optical preamplifier has three identical channels, each of which has a 40 mW, 658nm class IIIb laser source and a photo detector. It is used with light probes built by Hood Technology Corporation using ST optical connectors. The preamp is powered by the data console through a 9-pin sub-D cable. The detector electronics have user selectable gains and filter settings. The buffered output can drive long cables (up to at least 80m) to the data console. The physical shape of the preamplifier mitigates the possibility of accidental laser exposure.
Figure 1 : Hood Technology manufactures two types of preamplifiers. The eddy current preamp (left) is used for Hood Technology eddy current sensors or third party sensors via a BNC input. Optical preamp (right) contains lasers and photodiodes for Hood Technology BVM optical probes.