Raspberry Jam Universal Digitizer

Design

The Raspberry Jam digitizer was designed to work with most seismic sensors and supports 3-channels of single-ended and differential-ended signal inputs, passive and active sensors. By default, the Raspberry Jam comes pre-configured for passive sensors.

Channels (as labelled on PCB board):

Channel # Resistors Capacitors
1 R13,R14,R15,R16,R24 C29,C30,C31,C32
2 R22,R34,R35,R37.R38 C23,C24,C58,C59
3 R30,R52,R53,R55,R56 C33,C34,C62,C63

Component Groups:

Group Sensor Type Componentes
R[damp] Passive Damping Resistors: R22,R24,R30
R[a] Active R13,R14,R35,R37,R53,R55
R[b] Active R15,R16,R34,R38,R52,R56
C[a] Active Filter Capacitors: C23,C29,C31,C33,C59,C63
C[b] Active Filter Capacitors: C24,C30,C32,C34,C58,C62

Example Passive Sensors

Passive sensors (e.g., Geophones) only need a damping resistor (Group R[damp]). To determine the appropriate R[damp] resistor values, refer to the manufacturer’s data sheet. The other resistors in Groups R[a] and R[b] should be shorted out (0 Ohm resistor) and the filter capacitors in Groups C[a] and C[b], absent.

Examples of passive sensors that Raspberry Jam is compatible with:

Manufacturer Sensor Notes
ASIR A_F2-GS-70  
Geotech

S-13

GS-13[BH]

GS-21

 
Metry

F41-15.0

F50-4.5

F72-[2.0,4.5]

G88-[2.0,4.5]

G202-1.0

G110-1.0

previously IESE
Sercel L-4C previously Mark Products

Example Active sensors

The Raspberry Jam is compatible with the following active sensors and many more:

Manufacturer Sensor Notes
Chaparral

Model [25,25/21]

Model 50

Model 50a

Model 60/64; 60Vx

Model 60UHP

None

Assuming 40V pk-pk Diff. output; data sheet is inconclusive

None

Sensor is 44V pk-pk Diff. When used with 40V pk-pk Diff input, signal will clip at ~90% of sensor’s full-scale

36V pk-pk Diff. actual. Use 40V Diff input.

Geotech

KS-[1,2000,5400]

PA23

S-230

S-13 and other passive sensors

None

Assuming 40 V differential output

Assuming 40 V differential output

See below

Guralp

[3,5T,6,40] Series

Fortis

None

None

Kinemetrics

Episensor [2,ES-T,ES-U2]

HypoSensors (FBA ES-DH)

SBEPI (202)

We are guessing at what the actual value is, which is 40V Diff input. The +/-5V Diff input is not supported.

None

None

Lennartz LE-3D[lite/5s] MKIII 40V input comes close though the dynamic range is reduced. Better would be a 30V input range.
Metrozet MBB-[1/2] None
Nanometrics

Trillium Compact[PH,AT]

Trillium 120[Q/QA]

None

None

RefTek (Trimble)

151B-120

147A

None

None

Seismowave

LP[ZA,HA]

MB3 A

Assume output is 40V pk-pk Diff., but would be probably better served with a 50V pk-pk Diff. input structure.

Assume output is 40V pk-pk Diff., but would be probably better served with a 50V pk-pk Diff. input structure.

Steckeisen STS[2,2.5,5A,6A] Unsure what output level actually is. Assume output is 40V pk-pk Diff., but would be probably better served with a 50V pk-pk Diff. input structure.

Note

We assume that, in the seismology world, “40V peak-to-peak differential” output means that the output voltage of each signal line is swinging +/- 10 Volts with respect to ground. We have made this example list with that definition in mind, though it seems that in the seismology world the manufacturers are not consistent with how they specify the output level. In the end, the client is responsible for researching the solution and removing ambiguity surrounding how the manufacturer of their sensor(s) define the output level.

As most sensors on the seismology market have input voltages of 40V (Differential), resistors for this input range are specified below. If you have a non-40V special case, email us and we will send you the appropriate resistor values. Through-hole mountings are provided for resistors and capacitors to make it easy for electronics engineers and power users/ Do-It-Yourselfers to swap out components.

Filter capacitors can also included to provide, for example, a single-pole low-pass filter at 50 Hz. This was done to provide some minimal protection to keep 50/60 Hz electrical noise out of the system.

Recommended component values for active sensors with 40V Differential outputs:

Group Componentes Part Value Manufacturer Part # Digikey Part #
R[a] R13,R14,R35,R37,R53,R55 33kOhm, 0.1%, 1/8Watt, 25ppm MFP-25BRD52-33K 33KADCT-ND
R[b] R15,R16,R34,R38,R52,R56 12kOhm, 0.1%, 1/4Watt, 25ppm MFP-25BRD52-12K 12KADCT-ND
R[damp] Damping Resistors (Optional): R22,R24,R30 Do not include Do not include Do not include
C[a] Filter Capacitors: C23,C29,C31,C33,C59,C63 0.47uF, 5%, 63VDC R82DC3470SH60J 399-11865-1-ND
C[b] Filter Capacitors: C24,C30,C32,C34,C58,C62 0.22uF, 5%, 63VDC R82DC3220AA60J 399-9686-ND

Note

Active sensors must be externally powered.