Digitimer DG2A vs SPP-400: A Practical Comparison of Our Trigger Generators

Since its launch in 2004, the updated Digitimer DG2A has provided a simple, standalone trigger source compatible with the full range of Digitimer stimulators, as well as any device that accepts a TTL trigger input.

The DG2A can operate in free-run, single-pulse, or single burst/train modes, and includes an adjustable delayed pulse option.  This makes it particularly useful for paired-pulse protocols or experiments investigating effective refractory periods.

The DG2A’s simplicity is one of its main strengths, especially for applications that do not require the precision of a DAQ-based trigger system.  However, its infinitely adjustable analogue control dials limit the reproducibility of settings between experiments and users, which makes the DG2A less suitable for more demanding applications.

The new SPP-400 Digital Trigger Generator bridges the gap between the straightforward operation of the DG2A and the high precision offered by software-controlled DAQ devices with digital trigger outputs.  While the SPP-400 is not intended to replace the advanced capabilities of a full DAQ system, it provides a significant upgrade where rapid, precise adjustment of trigger parameters is required.  In this blog post, we compare the DG2A and SPP-400 to help you determine which is best suited to your research and experimental setup.

What are Digitimer trigger generators used for?

In many areas of neuroscience and physiological research, precise and flexible electrical stimulation is crucial.  Trigger generators play a central role in synchronizing stimuli, controlling external hardware, and enabling repeatable experimental sequences.  Many life science researchers can use their data acquisition systems to control stimulus delivery, but where electrical stimulation is used in the absence of any biological signal recording, this sort of hardware may not be available.  In these cases, a relatively low-cost stimulator trigger source can meet their needs.  With the launch of the SPP-400 we now have two units that can be considered for such tasks.  While both generate timing signals for experimentation, they offer different capabilities and user experiences.

Core Functionality: What Both Trigger Generators Offer

The DG2A and the SPP-400 share several key features:

• Adjustable Pulse Generation – Both devices allow users to produce electrical trigger pulses with configurable repetition characteristics.

• User Interfaces – Each unit provides a front-panel interface for adjusting timing parameters, though the approach differs between analog dial and digital controls.

• External Synchronization – Both can integrate with other lab equipment via trigger inputs and outputs, making them suitable for multi-device setups.

• Robust Build Quality – Designed for regular use in research environments, both are reliable and physically compact trigger sources.

In essence, both units accomplish the basic goal of supplying reliable timing triggers — but how and how flexibly they do it separates them.

Analog Simplicity vs. Digital Precision

The DG2A is a tried-and-tested analogue trigger generator.  It’s straightforward, easy to use, and excellent for standard pulse generation tasks.  Analogue controls provide immediate tactile adjustment of repetition rate, burst duration and delay, making it quick to set up in familiar routines.

However, analog controls have some limitations: fine, repeatable settings can be harder to dial in, and more complex timing sequences aren’t supported.  In contrast, the SPP-400 adopts a fully digital architecture.  This fundamentally changes the way users interact with the device and what it can offer:

• Menu-driven digital interface allows precise numerical entry of pulse and burst parameters, including the number of pulses or bursts.

• Stored configurations can be recalled quickly, improving reproducibility between experiments.

• Displayed parameters allow users to confirm settings visually and even store/recall them for future use.

For labs where experimental repeatability and cross-session comparability are essential, the benefits of the SPP-400 are more than niceties — they should be regarded as absolute requirements.

The SPP-400 Adds Multiple Channels, Repeating Bursts and Adjustable Output

The DG2A provides a single channel for pulse output with a fixed pulse amplitude and duration.  This is perfectly suitable for simple triggering tasks, such as a single burst of pulses or “free-run” constant triggering, but the SPP-400 adds features that enhance the versatility of the device.

• Inclusion of a Second Output Channel gives the user the ability to trigger two different devices with different timing patterns.  This means the SPP-400 can be use for applications that might require two different stimulators which require different trigger protocols (e.g. TMS and electrical).
• Channel Linking makes it possible to set the SPP-400 to deliver repeating bursts of pulses, with control over the number of bursts or pulses within each burst.
• Unlike the DG2A, the SPP-400 output pulses are not fixed in duration or amplitude, meaning it can be used as more than a basic trigger source.  With pulse duration adjustable between 0.01ms and 999.9ms and voltage adjustable between 0 and 10V, the SPP-400 can be used as a non-isolated stimulator or to drive other hardware such as LEDs.

Choosing the Right Tool for Your Lab

In evaluating the DG2A and SPP-400, it helps to think in terms of needs versus capabilities:

• If your work involves simple timing pulses with occasional adjustments and you can acccept some setting imprecision, then the DG2A delivers everything you need with minimal fuss.

• If your experiments can make use of multi-channel control, repeated bursts, or highly reproducible timing, the SPP-400’s digital precision and expanded feature set make it a superior choice.

The extra channel and digital control of the SPP-400 aren’t just incremental upgrades — they represent a shift toward greater experimental flexibility and control, all within a compact standalone device.

Both the Digitimer DG2A and the SPP-400 are capable trigger generators that serve essential roles in research labs.  However, for users seeking advanced features like multi-channel triggering, repeating pulse bursts, and the reproducibility that digital control enables, the SPP-400 offers clear advantages.  Whether you are optimizing experimental workflows, scaling up your setup, or simply demanding tighter control over timing parameters, the SPP-400 stands out as a modern, versatile choice.

If you have any questions specific to your trigger requirements or would like a quote for either device, please don’t hesitate to contact Digitimer or one of our representatives.