Dave Telling

Dave Telling, Electronics Engineer

Dave Telling Electronics Engineer Mr. Gasket Inc.

According to Dave Telling, an electronic engineer for Dana Engine Controls/Mr.Gasket, digital and analog systems can generally give the same result, but there are some fundamental differences in the way each type operates."Analog systems, which have been around for decades, use individual transistors, resistors, capacitors, diodes, etc., to perform the different ignition system functions."

Telling says each individual function requires the addition of more circuitry."In contrast, digital systems normally use a device called a 'microcontroller' to do the same things.A microcontroller is an integrated circuit that combines a microprocessor with different types of memory and input/output systems.Although all digital systems require some kind of analog support circuitry, virtually all of the major functions are performed in the microcontroller chip," says Telling.

MSD Ignition's Todd Ryden says although analog ignitions and digital ignitions share many of the same components, some of the differences of the two ignitions are in the use of discrete components."The discrete circuits of the analog ignition are used for input signal conditioning, such as the mag-pickup input and points input, multiple-spark generation and converter drive, timing retard control and rev-limiting control of the output," states Ryden.

Some of these circuits require calibration during manufacturing to meet specific operating performance specifications.

"The number of circuits that effect performance are higher in the analog ignition because of the need to check and calibrate multi-spark, rev-limiter, and timing-retard circuits," Ryden says, adding that integrated circuits include microcontrollers in the digital ignitions.
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However, digital systems can provide an overall performance increase by ensuring that rpm limits, timing advance curves and retards, rpm switches, etc., are as accurate and repeatable as possible," explains Telling, adding that this translates into more consistent runs.

Holley's Held says with the addition of digital electronics to control the analog high-voltage circuitry, you can expect better consistency unit to unit and day to day.

"The unit will always operate at peak performance, which is why the auto companies have all gone to digital systems," says Held.

Another major advantage that digital systems have is that you can provide a large number of functions without adding extra weight and space.

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Telling agrees, and explains that digital systems normally provide much more functionality in a single package and it is important to look at the overall system equivalent cost to accurately compare units.

"If you take a modern digital ignition system with multiple-rpm limits, multiple-timing retards, rpm switches, etc., you will find that digital systems are much less expensive," Telling says."If all you need is a very basic ignition system without the bells and whistles, then the cost difference is less.However, as seen with some of our recent offerings, there are still digitally controlled basic ignition systems available that are very cost-competitive."

Holley's Held says although it seems going digital does cost about 20% to 30% more up front, the benefits far outweigh the cost difference.

"Digital is extremely accurate in its firing capabilities which increases horsepower and torque, and digital units offer many more features in a much more compact unit," Held says.
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"We combine specific requests from our customers with input from our racing services personnel to determine what our products will do," explains Telling."For example, we found that customers did not like the DIP switch method of setting rpm limits.When at the track and trying to do seven things at once, they were making mistakes in setting the rpm limiters.Because of this, we decided to go to a completely different user interface that has LED number displays and pushbuttons to set the different functions."

Held says consulting with drivers is what led to his company's ICT with Launch Control system.