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DCA75 Semiconductor Analyser



Building on the continued success of our existing component identification and analysis instruments, the DCA Pro brings an array of exciting new features for the hobbyist and professional alike.
Key Features
The DCA Pro is an advanced new design that features a graphics display, USB communications, PC Software and an enhanced component identification library.

The DCA Pro supports all the components that the popular Peak Atlas DCA55 supports, but adds plenty more. Components supported include:

  • Transistors (including Darlingtons), Silicon and Germanium types. Measures gain, VBE and leakage.
  • MOSFETs, enhancement mode and depletion mode types. Measure on-threshold (at 5mA) and approx transconductance (for span of 3mA-5mA).
  • JFETs, including normally off SiC types. Measures pinch-off voltage (at 1uA) and approx transconductance (for span of 3mA-5mA).
  • IGBTs (insulated gate bipolar transistors). Measures on-threshold (at 5mA).
  • Diodes and Diode networks.
  • LEDs and bicolour LEDs (2 lead and 3 lead types).
  • Zener Diodes with measurement of zener voltage up to 9V at 5mA.
  • Voltage regulators (measures regulation voltage <8V, drop-out voltage, quiescent current). Note that some regulators are not stable without their decoupling caps and/or minimum load and cannot be tested by the DCA75.
  • Triacs and Thyristors that require less than 10mA of gate current and holding current.
Stand-alone or with a PC
The instrument can be used stand-alone or connected to a PC. Either way, the DCA Pro will automatically identify the component type, identify the pinout and also measure a range of component parameters such as transistor gain, leakage, MOSFET and IGBT threshold voltages, pn characteristics and much more.
Curve Tracing 
When connected to a PC using the supplied USB cable, a range of low current curve-tracing functions can be performed. Various graph types are available, with more to follow:

  • Bipolar transistor output characteristics, IC vs VCE.
  • Bipolar transistor gain characteristics, HFE vs VCE.
  • Bipolar transistor gain characteristics, HFE vs IC.
  • MOSFET and IGBT output function, ID vs VDS.
  • MOSFET and IGBT transfer function, ID vs VGS.
  • JFET output function, ID vs VDS.
  • JFET transfer function, ID vs VGS.
  • Voltage regulator, VOUT vs VIN.
  • PN junction I/V curves, forward and reverse options (for Zener diodes).

Curve tracing is performed using test parameters in the range of +/-12V, +/-12mA. All curve-tracing data can be instantly pasted into Excel© for further graphing and analysis. PC Software is included with the DCA Pro on a Peak USB memory stick. Software designed for Windows XP, Vista, Windows 7 and Windows 8 (automatically runs in Desktop Mode).

What\\\\\\\’s included?

  • DCA Pro instrument.
  • AAA Alkaline Battery.
  • Micro USB cable (approx 1m).
  • PC Software on USB Flash Drive (512MB).
  • Comprehensive printed user guide.

A Selection of PC Screen-Shots
TIP121 Darlington with internal resistors and diode G4BC20U N-Ch IGBT
Common Anode Bicolour LED BTS141 N-Ch MOSFET (Smart type with gate protection)
Comparing LED colours – all with appropriately coloured plots 2N5401 PNP Transistor Output Characteristics
Comparing voltage regulators Comparing Zener diodes using reverse PN analysis
J111 N-Ch JFET Transfer Characteristic OC71 PNP Germanium gain variation
DCA Pro – A view inside – Display side DCA Pro – A view inside – Surface mount side
Atlas DCA and DCA Pro Comparison
Feature Atlas DCA Atlas DCA Pro
Display type 16 x 2 Alphanumeric 122 x 32 Graphic
Communications USB (Win USB built-in driver)
Power supply 1 x GP23 12V battery 1 x AAA and USB power
Test Signals Range (typ) +/-5V, +/-5mA +/-12V, +/-12mA
Test Signal Resolution 10 bits 12 bits
Voltage measurement resolution 20mV 3mV
Diode / LED support Yes Yes
Transistor support Yes Yes
MOSFET support Yes Yes
IGBT support Yes
JFET support Yes Yes
Zener diode analysis Yes
Voltage regulator analysis Yes
JFET pinch-off measurement Yes
JFET on-threshold measurement Yes
JFET transconductance Yes
Depletion mode threshold measurement Yes
Saturation voltage measurement Yes
Leakage current measurement Yes Yes
Online upgradeable firmware Yes
Online upgradeable PC software N/A Yes
Sounder Yes (with mute on/off)
Atlas DCA75 – Frequently Asked Questions (FAQs)
Is the DCA75 ok with germanium transistors, can it measure leakage current and does it take into account the leakage current for it\\\\\\\’s gain measurement? Yes. The DCA75 will detect the germanium (or silicon) type of semiconductor. It will measure leakage current and it takes that leakage into account when measuring gain (unlike most multimeter HFEmeasurements).
I\\\\\\\’ve noticed the leakage current of my germanium transistor gradually drop with each subsequent measurement. Is the battery failing or something else wrong? Leakage current is extremely temperature dependent and particularly noticeable for germaniums as the current is fairly high to start with. The leakage current can double for just a 5°C increase in temperature. So after some handling, the transistor temperature slowly falls and can lead to a decreasing leakage current. That\\\\\\\’s completely normal and correct. Additionally, DCA75 test currents are completely independent of battery condition.
The Collector and Emitter of my germanium transistor is showing the wrong way round, is the DCA75 wrong? If the leakage current of the germanium transistor is quite high (due to warming from your fingers for example), the DCA75 can reject the \\\\\\\”correct\\\\\\\” pinout. However, it will then search for all other device types and configurations. It can, in those circumstances, find a transistor of opposite type (NPN/PNP) and with the C-E swapped (although gain can be very low). Tests in a simple circuit confirm that you can get a germanium transistor to work, with some gain, in that way. So the DCA75 is not wrong, it\\\\\\\’s just found a configuration that yields a low leakage current. Try keeping your transistor cool during testing to avoid this situation.
Can the Atlas DCA75 measure Zener diodes? Yes. The DCA75 can test Zener diodes up to around 11V. Zeners with a reverse voltage of less than around 8V will be tested at 5mA, higher voltage ones may be tested at a lower test current. The test current is confirmed on the display.
Can I use the DCA75 to match transistors? Yes. The main parameters that you may be interested in are HFE and VBE. Both of these parameters are measured by the DCA75. This enables you to group your transistors that have similar gain figures for example. Additionally, the use of the curve tracing facility allows even greater flexibility for your desired matching requirements.
What will the DCA75 show if my component is faulty? Generally, the DCA75 would show \\\\\\\”No component found\\\\\\\”. Sometimes it may still be able to see a pn (diode) junction within the component you\\\\\\\’re testing, in which case it would display \\\\\\\”Diode or diode junction(s)\\\\\\\”. If there is a short circuit within your component then the DCA75 will display \\\\\\\”Short circuit on RED GREEN\\\\\\\” for example.
Can my Atlas DCA75 be upgraded online? Yes. The PC software (available here) will check your instrument to make sure it\\\\\\\’s got the latest firmware, it will then offer to upgrade it for you.
Why can\\\\\\\’t the DCA75 analyse triacs or thyristors that need higher currents than 10mA? The test currents of the DCA75 are deliberately low to avoid damage to any potentially random component that can be connected any way round. The Peak Atlas SCR is aimed specifically at analysing a wide range of triacs and thyristors that require test currents from less than 100uA up to 100mA.
My voltage regulator won\\\\\\\’t test out correctly on the DCA75, what\\\\\\\’s wrong? There are many varieties of voltage regulator available and some can\\\\\\\’t be tested on the DCA75. Firstly, the regulator voltage needs to be around 8V or lower for it to be testable. Secondly, there are some regulators that just aren\\\\\\\’t stable unless they\\\\\\\’re in their intended circuit with decoupling caps and a suitable load.
Will you have software that can run on a Mac or under Linux available? We don\\\\\\\’t have immediate plans for releasing non-Windows software, although we are investigating the possibility.
I have a suggestion for a new supported component type or new feature, what can you do? We\\\\\\\’d love to hear any new component or new feature suggestions. We\\\\\\\’re a flexible company and we\\\\\\\’ll do our best to implement new features when possible.
How long is the warranty period? All our products now have a warranty of 24 months. This doesn\\\\\\\’t cover accidental damage or abuse however.
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