Product type: Electronics kit
Manufacturer: Velleman http://www.velleman.be/
Product information web pages:
http://www.velleman.be/ot/en/product/view/?id=9360
http://www.elfa.se/elfa-bin/setpage.pl? ... 014143.htm
http://www.velleman.be/downloads/0/illu ... _k7000.pdf
Price: 17.70 Euros (http://www.elfa.se/)
Product description:
This signal tracer /injector has been designed to inject or detect a specific signal into an audio circuit in need of repair (such as amplifiers, radios, tone controls, ...) so as to detect the fault.
The circuit board consists of an oscillator with a fixed frequency (1000 Hz) and adjustable output level, and amplifier with adjustable input sensitivity and output for speaker. The oscillator is connected to the equipment at some suitable place, and the amplifier input is then connected to different points in the signal-chain. The amplifier's input impedance is high, which prevents loads on the equipment that is being tested.
Supply voltage: 9–12 Vdc/7–9 Vac
Power consumption: 150 mA max
Oscillator
Frequency: 1000 Hz
Output level, rms: 0–2.5 V
Output impedance: 1.5 kΩ
Amplifier
Output power: 0.5 W/8 Ω
Load impedance: 4–8 Ω
Input sensitivity, rms: 3.5 mV to 10 V
Input impedance: 50 kΩ
Gain: 40 dB
Dimensions: 60×53×29 mm (excl pot axis)
My comments:
the kit works pretty well as advertised. The kit was easy to soldort togther and comes all necessary instructions. The kit can be powered with 9V battery.
The oscillator is quite simple transistor based sinewave oscillator. It gives quite acceptable 1 kHz sinwave output. The output level is nicely adjutable. The position of output adjustment has some effect on the output impedance. Anyway OK signal source.
The amplifier part works pretty much as advertised. You can trace signal with it. But there is one usability limitation on this kit: There seems to be some notiveable crosstalk from the oscillator to amplifier. This means that even if you use well shielded connection cables, some part of oscillator signal can be heard from amplifier output all the time no matter if amplifier is connected to signal source or not. This limits the usability on low level signal tracing. A little bit dissappointment.
Modifications I made to the kit:
I added a headphone output to this kit. A suitable resies resistor from amplifier IC output to headphone output makes this easily.
Another addition was to add as switch that shuts down the oscillator par when it is not needed. When oscillator is shut down, there will not be annoying oscillator sound on the output signal all the time, and you can trace lower level signals easily (signals from other sources). scillator can be shut down by cutting power to oscillator part or shorting for example R2 or R4 resistor.
