Information and Enhancements/Corrections on the Philips EE2000/EE2001 series

Keywords: Philips EE kits, EE2000 series, EE2001 series, LM3900, EE2005 superhets, IF Coil data

This page presents additional information sources and/or enhancements/corrections based on my personal experiences. Please respond if you have (other) improvements or information sources as well.

EE2000 Series (applies also to EE1000 and EE3000 series)


1.1 (EE2003/4/5/6) Suggested redesign of two-transistor audio amplifier stages

In many constructions a two-stage audio amplifier is used to drive a loudspeaker. In almost all cases (for example the EE2003 medium wave receiver 5.02, the only exception is the 5.03 SW receiver) a design is used in which the 10K potentiometer (volume control) drives two subsequent BC238 transistor stages, the latter tied together directly via a 4.7uF or 10uF elco. This approach has the following drawbacks:

A better approach is to change the location of the volume control in the circuits; the 10K potentiometer should be put in between the two white transistors instead of before them. The SW receiver on this website shows such a configuration, as well as the way to couple the audio circuit with a preceding circuit. I have applied it succesfully to the EE2005 superhets; it eliminates the disturbances almost completely and provides for stable operation of the superhet designs.


1.2 (EE2005) Trimming of IF coils

The red transformers in the EE2005 kit contain a small ferrite bead whose position can be changed by turning it with a small (preferrably plastic) screwdriver. In this way the coils can be trimmed towards equal frequency, which is very important for the IF signal strength applied to the diode detector of the superhet designs. The best way to trim the transformers is the following approach:

  1. Put the beads in the red transformers in approximately the middle position (so that they can be turned in both directions)
  2. Build the superhet receiver, calibrate it using the directions in the manual and search for a relatively strong radio station.
  3. Adjust the second red transformer (the one closest to the diode detector part, adjust by turning its ferrite bead) for maximum perfomance

In this way the diode detector get the maximum amount of IF signal, which is very important for the operation of the germanium diode detector as it needs a signal of more than 0.3V to operate properly ( signals with a forward diode drop of less than 0.3V will not be demodulated at all).


1.3 (EE2005) Better stability, perfomance and audio quality for the EE2005 superhet receivers

I have seen several reports of disappointing/bad or even absent performance of the EE2005 superhet receivers, and I experienced some problems too. I have found the combination of the following measures to solve all problems:


1.4 (EE2005 2nd version with new, modern coils [applies also to EE3004, EE2000GK]) IF and OSC Coil Data

At the end of the lifetime of the EE2000 series the EE2005 coils types that were already present in the EE1000 series (and were tailor-made by Philips for the EE series) were replaced by modern types. The manual update leaflet included in the kit does not specify any technical information on these coils. A variety of IF and oscillator coils currently exists on the market, and here I try to explain the differences between them and provide some technical data that I am confident of and which seems to apply to the coils in the Philips EE kits:


1.5 (EE2005 2nd version with new, modern coils [applies also to EE3004, EE2000GK]) Errors/deficiencies in manual update leaflet

In the kits that contain the new type of coils a leaflet is included that describes some updates of the original EE2005 circuit diagrams that use these coils, and some extensions of the various receivers. However the leaflet contains some flaws, and does not provide any technical data on these coils (but see item 1.4 above on this matter). Here I present some information and updates:

EE2001 Series


2.1 Information on the LM3900 Norton OpAmp

In the EE2001 series constructions the LM3900 plays a central role. It is quite an old chip (released in 1972 by National Semiconductor, still in production by Texas Instruments); in fact is was the first chip that provided four opamp gates on a single chip, which was possible because of the relative simplicity of the gates when compared to the "de facto standard" 741 opamp. Since internet access has almost become a commodity we now have the opportunity to have access to this well-documented chip. Here follow links to the LM3900 Data Sheet containing electrical characteristics, and the important AN-72 Application Note (43 pages!) which contains a wealth of basic LM3900 circuits (some interesting ones are not in the EE2010/13 manual).

It is important to stress that the LM3900 is not a regular quad opamp: instead of Vout = A*(Vin+ - Vin-) (which is what a regular opamp does; the output voltage equals A times the voltage difference between the +/- input terminals) the LM3900 basically delivers Vout = A*(Iin+ - Iin-), i.e. the output voltage equals A times the input current difference between the +/- inputs. As a consequence the LM3900 as low-impedance inputs, in contrast to regular opamps which should have high-impedance inputs. However, in the EE2001 series manuals the LM3900 circuits are always designed and explained as if the chip contained regular opamps (see issues 2.2 and 2.3 for the consequences)

For an interesting explanation between regular OpAmps and "Norton"-type amplifiers like the LM3900 see the following link (especially chapters 8 and 9 on voltage vs. current differencing amplifiers):

The LM359: A successor of the LM3900

Although not a pin-compatible replacement, the LM359 is a successor of the LM3900 with improved technical specifications:

The LM359 is a dual "programmable" opamp in a 14-pin package. The two opamps each have two extra input pins for external frequency compensation. This chip is interesting for designers who are accustomed to the LM3900 but need a much faster chip (all LM3900 circuits can be applied with the LM359 too). Please refer to the following links for detailed information:


2.2 {EE2010/13) Flaws in the explanation of LM3900 circuits in the EE-manuals


2.3 (EE201X) Starting problems of LM3900 multivibrator circuits


2.4 (EE2015) Powering suggestions

The EE2015 kits contain chips that are implemented in the original TTL technology. As a result the EE2015 circuits consume quite some battery power (I didn't measure) and consequently the batteries get exhausted quite rapidly (which I do remember). Currently there are a few powering options available:


2.5 (EE2015) Erroneous LED connections to 7402 outputs

The EE2015 kit uses logic gates which have different output ports. The 7405 inverter has so-called "open collector" outputs, which means that the output of this gate merely contains a switch connected to ground. As a result a pull-up resistor is needed to drive a device like a led or a transistor, as shown in the figure below in case (a). Most other gates however (7402,7490) have active-drive outputs, which means that these outputs themselves directly drive a device whithout the need for pull-ups, as shown in case (b).

In the EE2015 manual however , concerning all circuits, the 7402 active-drive output circuits are erroneously designed as if they were open-collector outputs, i.e in fashion (a) instead of (b). As a result the current flow through the device is limited only by the output-drive capability of the 7402, not by the protective resistor in case (b), and this may in the end damage the LED or other attached device. So, case (b) descibes the correct way of treating 7402 outputs, whereas case (a) pertains only to 7405 outputs.

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