Perplexing DC voltage

Dan Schmidt's picture

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Joined: Mar 28, 2020

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Perplexing DC voltage
March 28, 2020 - 4:56am

Hi All, I hope I’ve selected the correct forum. This is my first time posting.
Here goes: I have a VHF radio that I know works on a boat. I know this because I rigged up (alligator clips and wires coming out the end) a variable voltage house plug-in transformer (the kind you would buy from Radio Shack if you lost the charger for your Black and Decker cordless drill), set it on 12 volts, connected it to the two radio’s connectors, plugged it in and voilà, it worked. Voltage output on the aforementioned rig is about 12.5v (+/- 0.05v). On the boat, voltage at the radio’s plug ranges from 12.25 – 13.5. The odd thing is, when I plug in the radio with power to the plug, it doesn’t work. I know it’s getting power because I put my meter on the back of the plug as it’s plugged into the radio and power is present, again 12.25 – 13.5 volts. This radio is not new to the boat and has worked off the boat’s power in the past. I’ve gone through this procedure several times and got the same results each time. As the subject line says, this is very perplexing. If anyone can off some suggestions, I would greatly appreciate it. Thanks

Aswinth Raj's picture

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May be your crude power supply is too noisy
March 30, 2020 - 1:36pm

RF modules are very sensitive to power noise. A cheap power adapter or a DIY adapter will have a lot of power noise. Maybe this noise is affecting the RF signals from the module.

Try using an electrolytic capacitor (like 24V and 10uf) across the power rail and see if it works 

marry roser's picture

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Direct current (DC) is the
April 8, 2020 - 2:53pm

Direct current (DC) is the unidirectional flow of an electric charge. An electrochemical cell is a prime example of DC power. Direct current may flow through a conductor such as a wire, but can also flow through semiconductors, insulators, or even through a vacuum as in electron or ion beams. The electric current flows in a constant direction, distinguishing it from alternating current. A term formerly used for this type of current was galvanic current.
The abbreviations AC and DC are often used to mean simply alternating and direct, as when they modify current or voltage.

Direct current may be converted from an alternating current supply by use of a rectifier, which contains electronic elements (usually) or electromechanical elements (historically) that allow current to flow only in one direction. Direct current may be converted into alternating current via an inverter.
Direct current has many uses, from the charging of batteries to large power supplies for electronic systems, motors, and more. Very large quantities of electrical energy provided via direct-current are used in smelting of aluminum and other electrochemical processes.

jaksonlee's picture

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Joined: Nov 07, 2019

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Direct current (DC) is the
April 26, 2020 - 10:30pm

Direct current (DC) is the unidirectional flow of an electric charge. An electrochemical cell is a prime example of DC power. Direct current may flow through a conductor such as a wire, but can also flow through semiconductors, insulators, or even through a vacuum as in electron or ion beams. The electric current flows in a constant direction, distinguishing it from alternating current. A term formerly used for this type of current was galvanic current.
Direct current has many uses, from the charging of batteries to large power supplies for electronic systems, motors, and more. Very large quantities of electrical energy provided via direct-current are used in smelting of aluminum and other electrochemical processes.

Muhammad Umar's picture

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Joined: Apr 09, 2020

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DC Source
May 15, 2020 - 4:56pm

The power source you mentioned, you are using for powering up your radio module is not suitable for the radio modules because of the reason that there contains noise signals in these kind of power adaptors. Try using specified batteries, recommend for radio modules or some power adaptor with lowest noise. But also you can try by adding an electrolytic capacitor in power rail, for that use capacitors if voltage ratings of 16V or 25V. There can be any of the capacitance value just check for the best option to reduce the noise signals. Here I would like to recommend you to connect with the SSLA platform, from where you can get further assistance about your project from their technical support team.

Technical Shahzad's picture

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Power Source (DC)
May 27, 2020 - 3:35pm

The power source you mentioned, you are using for powering up your radio module is not suitable for the radio modules because of the reason that there contains noise signals in these kind of power adaptors. Try using specified batteries, recommended for radio modules or some power adapter with lowest noise. But also you can try by adding an electrolytic capacitor in the power rail, for that use capacitors with voltage ratings of 16V or 25V. There can be any of the capacitance values, just check for the best option to reduce the noise signals. Here I would like to recommend you to connect with the Sierra Software Ltd. platform, from where you can get further assistance about your project from their technical support team.