If you do not allow these cookies we will not know when you have visited our site, and will not be able to monitor its performance. All information these cookies collect is aggregated and therefore anonymous. They help us to know which pages are the most and least popular and see how visitors move around the site. Performance Cookies: These cookies allow us to count visits and traffic sources so we can measure and improve the performance of our site. If you do not allow these cookies then some or all of these services may not function properly. They may be set by us or by third party providers whose services we have added to our pages. Functional Cookies: These cookies enable the website to provide enhanced functionality and personalization. These cookies do not store any personally identifiable information. You can set your browser to block or alert you about these cookies, but some parts of the site will not then work. ![]() They are usually only set in response to actions made by you which amount to a request for services, such as setting your privacy preferences, logging in or filling in forms. Strictly Necessary Cookies: (Always Active) These cookies are necessary for the website to function and cannot be switched off in our systems. After we finish updating our website, you will be able to set your cookie preferences. Substituting an op amp for the comparator in Figure 1 enables the audible alarm in this circuit to increase in volume as you approach the RF source.Īnalog Devices is in the process of updating our website. The audio level generated by this buzzer is proportional to the input voltage, so as the detector approaches a hidden bug, the MAX4480's output voltage increases, intensifying the alarm and making it easy to pinpoint the bug's location.įigure 2. You can adjust resistor R4 to obtain the desired gain and output-tone level. The MAX4480 then amplifies the MAX2015 output voltage (0.5V to 2.0V) to the range (0.75V to 3.0V) for driving the buzzer. Simply replace the MAX9075 comparator with the MAX4480 amplifier, configured for a gain of 1.5. (To avoid false alarms, you can fine-tune the reference voltage by adjusting resistor R2.) On detecting an RF signal, the MAX2015 triggers comparator MAX9075 to generate an output voltage of 3.0V, which in turn activates a loud buzzer.Ī modification to this circuit not only detects RF bugs it also locates their hidden positions (Figure 2). ![]() The reference voltage at the inverting terminal of the MAX9075 is preset to 0.6V by resistors R1 and R2. This voltage increases in proportion to the input RF power level, up to approximately 2.0V. This circuit sounds a buzzer alarm when it detects an RF signal in the range 100MHz to 3000MHz, above approximately -35dBm.Īt low input-power levels such as -35dBm at 3000MHz, the MAX2015 generates a DC output of approximately 0.5V. The log detector (the MAX2015) senses RF signals at pin INHI, and produces an output voltage on pin 8 proportional to the power level of the received signal.įigure 1. Received power levels can be as low as -35dBm or 0.32µW. The circuit in Figure 1 detects RF "bugs," such as hidden wireless cameras, eavesdropping microphones, and other spying devices that emit RF frequencies in the 100MHz to 3000MHz range. A modification to this circuit not only detects RF bugs, but also locates their hidden positions. This design idea showcases a circuit that detects RF \"bugs,\" such as hidden wireless cameras, eavesdropping microphones, and other spying devices that emit RF frequencies in the 100MHz to 3000MHz range.
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