PCB detectors

PCB  detectors

Diablo control make a detectors of all styles. Some have become industry standards, and some have adopted industry standards.

All detectors use 100% of Diablo Controls experience and expertise.

Diablo's professional rack detectors are prominent in many states in USA. You can trust Diablo as millions of americans do.


PCB cards

OEM Cards

Traffic rack cards

DSP15 PCB detector


Loop inductance 20µH to 1500µH (incl lead-in inductance)
Operating Temp -37°C to 74°C
Operating Voltage 10 to 30 volts AC or DC,
Operating Current 75mA max fail safe
40mA max fail secure>
Dimensions 74mm (D) x 104mm (W)
Relay contacts Presence 3A @ 125VAC, Form C
Pulse 3A @ 125VAC, Form A

DSF15 is a single loop card. Relay A is set for presence and relay B set for pulse.

This is a standard format 10 pin detector used in domestic applications since 1980's. There are various connector options. Suffix T is the versatile screw termnal version shown.  Suffix M with a male header is also popular. 

DSP15 pinout
Pin Function
1 Relay A, com
2 Relay A, N/C
3 Relay A, N/O
4 Relay B, com
5 Relay B, N/O
6 not used
7 +ve power
8 -ve power
9 Loop
10 Loop

DSP15 functions 

DSF15 is a single loop card. Noise filtering improves stability on noisy or troublesome sites. RelayA defaults to presence and relayB set for pulse.

This is a standard format 10 pin detector used in domestic applications since 1980's. Suffix T is the versatile screw termnal version shown.  Suffix M option with a Molex male header is also popular.

DSP15 can replace most 10 pin 'Molex' detectors. Terminal order is always the same. There is even a standard colour code for the 10 pins.

The detector self calibrates to the ferrous footprint on power up. Loop failure detection has an optional memory feature to detect intermitant loops..

The volt free relay contacts and a loop transformer give good isolation from lightning discharges through the ground loop.

DSP15 is an old school solid detector with new ideas. It will be your last best choice.

DSP15 sensitivity
0 4800ppm
1 3200ppm
2 2400ppm
3 1600ppm
4 1200ppm
5 800ppm
6 600ppm
7 400ppm
8 300ppm
9 200ppm

Set on 10 way rotary switch

DSP15 DIP functions

DIP 1 & 2       sets to one of 4 frequency ranges. Exact frequency is set by the physical layout of the loop, so DIPs set the range.

DIP 3          When output B is set to 'failure', default is to switch relay B while a loop fault persists. Setting DIP to 'retain memory' leaves the relay ON until reset.  

DIP 4          sets ambient creep. As conditions change a detector adjusts over time. Ambient ferrous objects will be nulled out over 30 mins with DIP4 OFF, or over several days with DIP 4 ON.

DIP 5&6     set relay B function. Options include a loop fail output (see DIP3). Pulse can be set when a vehicle arrives on the loop, or when it leaves the loop area. 

DIP 7         sensitivity boost is a hysterisis function. While a vehicle is detected, sensitivity is increased. The theshold for un-detect is lower. It is used for lorries whose tractor has a high mass, but the trailer has a high bed.

DIP 8 & 9    is used to extend a presence detection. For example, it can prevent a barrier arm decending between a car and a trailer. 

DIP 10      is a filter for brief activation of the loop. It must be activated for at least 2 secs before the relay switches, so excluding fast transit or spurrious activation.


JUMPER J2.   sets fail safe mode (instal J2) or fail safe mode (remove J2).

DSP15 DIP functions
Function DIP ON OFF
Frequency/td> 1 & 2 OFF + OFF = High frequency
ON + OFF = Mid hi frequency
OFF + ON = Mid lo frequency
ON + ON = Low frequency
Failure memory 3 retain failure
Presence 4 vehicle ignored
after days
vehicle ignored
after 30 mins
Relay B function/td> 5 & 6 OFF + OFF = Presence
ON + OFF = Pulse on entry
OFF + ON = Pulse on exit
ON + ON = Loop failure
Sensitivity boost 7 Sensivity
no boost
Release delay 8 & 9 OFF + OFF = no delay
ON + OFF = 2sec delay
OFF + ON = 5sec delay
ON + ON = 10sec delay
Activate delay 10 2sec before
no delay


GREEN is for power and loop diagnostics. LED is ON for normal operation. A blink indicates low voltage is too low. Flashing means the loop has open circuit or shart circuit fault. 

RED is the detect LED for relayB. 


The DSP22s is a dual channel card designed for old DoorKing openers. The channels have independant circuits. Four sensitivity levels can be set for each channel on the sens/reset button.

Each channel has power (green), and state (red) LEDs. In the case of a loop circuit failure, the green LED flashes slowly (2Hz) for an open circuit loop, or flash quickly (10Hz) for short circuit loop. 

Channel 1 is a solid state presence output. Channel 2 has a form C relay, and can be set as pulse with fail secure,  or presence with fail safe mode. 

The loop range is 20uH to 2mH.

DSP22s pinout
Pin Function
1 Loop 1
2 Loop 1
3 Loop 2
4 Loop 2
5 Chan2, N/O
6 Chan2, Com
7 Chan2, N/C
J1 board plug
Pin Function
1 12-30Vdc +
2 Ground
3 Output


The DSP22-2 is a dual channel card designed for DoorKing openers. Multiplexing channels improves noise tolerance, and allows placement of loops closer together than ever possible.

Sensitivity is set for each channel on a button. Each channel has power, and state LEDs, with loop fault diagnostics. 

Channel 1 is a solid state presence output. Channel 2 has a form C relay, and can be set as for normal loop pulse or a mini-loop pulse. 

The DSP-22-2 is fail-safe mode with fault memory to alerts user to past but recovered faults. There is a new flicker display on channel 2 in pulse mode. The LED is on during the pulse, reverts to flicker mode
while the channel is still detecting the vehicle.


DSP22-2 pinout
Pin Function
1 Loop 1
2 Loop 1
3 Loop 2
4 Loop 2
5 Chan2, Com
6 Chan2, N/O
7 Chan2, N/C
J1 board plug
Pin Function
1 14-27Vdc
2 Ground
3 Output

Traffic cards

Diablo control is the preferred supplier of 19" rack mounted detectors to many US states, and other nations. These traffic control workhorses are seldom seen by the public, but keep the country flowing, sans bouchant. 

Loop diagnostics

The red detect LED is ON when a vehicle is over the loop detection area. It only flashes briefly on VD909, but will remain on for VD906 and VD907

Green Power LED flashes once per second indicating the detector is powered and operating. The green LED is also for loop diagnostics. If the loop becomes disconnected the green LED flashes at 2 times per second. This LED will flash 10 times per second is the loop is shorted.

Most problems are loop faults. Inspect the ground around the loop for surface break up. To check for open circuit loops, un-plug the connector, then check resistance with a digital test meter. Resistance should be less than 100 ohms.

A temorary loop can be made with 15m of single core cable laid on top of the road surface. It will be sensitive to small movements but stable enough to test the detector module.  If this solves the problem you may need to replace the loop.

Loop installation is a well established road technique. We have published articles on this website. There are links below.

Loop installation
Multi-core loops