$210.00
DB1-128 Signal Amplifier & Fixed Frequency Divider — 12/24VDC
Use the DB1-128 when a compatible speedometer or tachometer signal is too weak
for the receiving instrument, or when the displayed reading is consistently an
exact supported multiple too high.
Typical problems it can solve
The module conditions a compatible input into a supply-level square wave and
selects one fixed division of ÷1, ÷2, ÷4, ÷8, ÷16, ÷32, ÷64 or ÷128.
Only one DIP switch may be ON at a time.
Is your correction an exact DB1-128 setting?
Enter the measured input and required output. The simulator shows the closest
divider, predicted result and the one DIP switch that should be ON.
Not for fine ratio correction: where the required correction is not
÷1, ÷2, ÷4, ÷8, ÷16, ÷32, ÷64 or ÷128, use a suitable adjustable ratio product instead.
Speedometer and tachometer signal conditioning
Signal Amplifier / Divider — 12/24VDC
bolec.com.au | sales@bolec.com.au | 0480 312 400
Electronic speedometers and tachometers calculate their reading from the frequency and shape of an incoming pulse signal. A conversion may fail when that signal is too weak for the new instrument, or when the source produces 2, 4, 8, 16, 32, 64 or 128 times more pulses than the instrument expects.
The DB1-128 solves those two specific problems: it conditions a compatible signal into a supply-level square wave and, when required, divides the frequency by one fixed power-of-two ratio selected with a single DIP switch.
A speedometer or tachometer does not read speed or RPM directly. It counts electrical pulses. The signal source and receiving instrument must agree on both signal quality and the number of pulses representing a given speed or RPM.
A magnetic pickup, alternator connection or auxiliary ignition output may not provide the waveform or amplitude expected by the replacement instrument.
DB1-128 action: condition a compatible input of 2 V p-p or greater into a square-wave output that rises approximately to the positive supply level.
For example, an instrument may show approximately 800 RPM when the verified value is 100 RPM. The source is producing eight times the frequency required.
DB1-128 action: select ÷8 by turning ON Switch 4 only, reducing 800 pulses to 100 pulses over the same period.
This can occur after a drivetrain, engine, alternator, instrument or dashboard conversion where both devices work, but their expected frequency relationship differs.
DB1-128 action: provide signal conditioning and a supported fixed divider when the required correction is exactly ÷1, ÷2, ÷4, ÷8, ÷16, ÷32, ÷64 or ÷128.
If the required relationship is something such as 0.875, 1.25 or another fine ratio, the DB1-128 cannot produce that exact correction.
Better option: use an adjustable ratio product such as the ERB205, subject to signal compatibility.
The examples below describe the type of problem the module can solve. They do not replace electrical testing or confirmation of the receiving instrument's requirements.
A compatible speed source may provide two or four times the pulse frequency expected by the instrument. Select ÷2 or ÷4 after confirming the measured relationship.
A consistent eight-to-one error points to a pulse-count mismatch rather than a random fault. A ÷8 setting may correct the frequency if the signals are compatible.
The DB1-128 may condition a compatible magnetic-pickup, alternator AC or electronic auxiliary signal into a supply-level square wave suitable for many inputs.
When a new engine, alternator, ECU or instrument cluster uses a different but exact power-of-two pulse relationship, one fixed divider can provide the required scaling.
The module can process compatible frequency signals used by diesel tachometers and other driven instruments in 12V or 24V negative-ground systems.
This usually requires further diagnosis. The DB1-128 only applies a fixed power-of-two division; it cannot repair a failing sensor or provide a fine arbitrary ratio.
Record input frequency, signal amplitude and waveform.
Compare the current reading with a verified desired reading.
Choose one supported divider using the simulator or switch table.
Test the completed installation throughout its operating range.
Enter a measured input value and the output value the instrument actually needs. The tool identifies the nearest fixed divider, predicts the result and shows the single DIP switch that would be ON.
Use the same units for both values. The DB1-128 can condition at ÷1 or divide by 2, 4, 8, 16, 32, 64 or 128.
Important: never turn on more than one divider switch at the same time. This tool selects a divider only; it does not confirm signal compatibility.
The required correction exactly matches one of the eight supported divider settings.
The nearest fixed divider is shown, but the predicted output does not exactly match the target.
The requested output is higher than the input or falls outside what a fixed ÷1 to ÷128 divider can achieve.
It cannot confirm waveform, amplitude, electrical compatibility, wiring condition or whether the original sensor and instrument are functioning correctly.
| Switch ON | Function | Output |
|---|---|---|
| 1 | Condition / ÷1 | Input ÷1 |
| 2 | ÷2 | Input ÷2 |
| 3 | ÷4 | Input ÷4 |
| 4 | ÷8 | Input ÷8 |
| 5 | ÷16 | Input ÷16 |
| 6 | ÷32 | Input ÷32 |
| 7 | ÷64 | Input ÷64 |
| 8 | ÷128 | Input ÷128 |
Use the connection drawing for the receiving instrument in addition to this general guide.
| IGN+ | Switched 12/24VDC supply, preferably through a 2 A fuse |
|---|---|
| GND | Good negative ground or earth |
| INPUT | Active wire from the magnetic pickup or compatible signal source |
| OUTPUT | Signal input terminal on the receiving instrument |
Installation by a qualified automotive electrician or instrument technician is recommended.
Only one switch may be ON at a time.
| Switch ON | Divider | Example with 800 Hz input |
|---|---|---|
| Switch 1 | Condition / ÷1 | 800 Hz |
| Switch 2 | ÷2 | 400 Hz |
| Switch 3 | ÷4 | 200 Hz |
| Switch 4 | ÷8 | 100 Hz |
| Switch 5 | ÷16 | 50 Hz |
| Switch 6 | ÷32 | 25 Hz |
| Switch 7 | ÷64 | 12.5 Hz |
| Switch 8 | ÷128 | 6.25 Hz |
Turn ON one divider switch only.
The controlled product document and markings on the supplied module take precedence.
| Part number / SKU | DB1-128 |
|---|---|
| Function | Signal conditioning and fixed frequency division |
| Supply | 12/24VDC negative ground |
| Input waveform | Sine or square wave |
| Input amplitude | 2 V p-p or greater |
| Input frequency | 0–10 kHz |
| Output | Square wave at approximately the positive supply level |
| Output rise time | ≤40 µs |
| Divider settings | ÷1, ÷2, ÷4, ÷8, ÷16, ÷32, ÷64 or ÷128 |
| Dimensions | Approximately 58 × 42 × 23 mm |
youtube.com/watch?v=5BSeMs7goHs
The signal needs conditioning or an exact fixed division by 1, 2, 4, 8, 16, 32, 64 or 128.
Two common signs are a compatible speed or RPM signal that is too weak for the receiving instrument, or a reading that is consistently an exact supported multiple too high, such as 2×, 4× or 8×.
No. It conditions and divides a compatible frequency signal. Sensor faults, open circuits, poor grounds and incompatible instruments must be diagnosed separately.
No. Switch 1 provides signal conditioning at ÷1 and the remaining switches reduce frequency. The DB1-128 does not multiply frequency.
Those are not DB1-128 settings. The available fixed values are 1, 2, 4, 8, 16, 32, 64 and 128. An adjustable ratio module may be more appropriate.
Each switch selects one complete divider mode. The installation guide specifically instructs the installer not to have more than one switch ON at the same time.
Confirm supply voltage, input waveform, peak-to-peak signal voltage, frequency range, current reading, verified desired reading and the receiving instrument's input requirements.
The direct PDF includes specifications, fitting instructions, wiring and DIP switch settings.
Read practical application notes and product guides from Bolec Electronics.
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