Over-Voltage Crowbar Protection for Ham TransceiversDesigned by 9H1LO in Malta
NOTICE - Back in stock with slight price rise, sorry for this but parts and shipping has gone through the roof and was taking a loss! For countries which show no-shipping method, please select your c…Read More…
NOTICE - Back in stock with slight price rise, sorry for this but parts and shipping has gone through the roof and was taking a loss! For countries which show no-shipping method, please select your country below and enter your email address and I will get a quote there and then as it is impossible to put every country and putting a flat rate doesn't make it fair, I do not profit on shipping
Most linear power supplies do not include a crowbar as over-voltage protection. Should the output pass transistors fail you risk your radio getting over 24V directly from the power supplies rectifier.
This circuit uses a 40TPS12 from Vishay which when triggered by the Zener diode will clamp the power supply to ground and blow the fuse, protecting your expensive radio from over-voltage.
This is available as a kit and supplied with the fuse size of your choice, as standard, a 25amp fuse is supplied, ask for a different value if you want and I will try to accommodate.
As standard the kit will clamp at around 18v +/- 1v, other voltages can be made available on request.
If you choose the ready-built & tested option: You can contact me to "tune" the values as close as possible to your wanted clamping voltage, this will be around +/- 0.5v though. If you wish I will apply conformal coating to the board FOC, but please request it if you want it, soldering to the terminals is still easy with a decent iron.
NO COMPROMISE ON PARTS QUALITY as this has to WORK 100% to save your radio, therefore all components are supplied from Farnell not cheap stuff from the far-east.
IMPORTANT NOTE: It is expected that you have basic soldering skills and basic circuit knowledge to mount this device, if you do not have this skill set please find some help from someone who does. Instructions are included and I can offer limited email support, though it is quite basic and easy to build and mount. Whilst this kit is designed to protect any connected equipment, due to the nature of its functionality and since this is a self-build and self-install kit, there is no guarantee on its functionality and I will not hold any responsibility or liability in the event of any damage to its connected equipment, power supplies, transceivers etc. The user is responsible to understand the schematics and installation instructions.
FINAL DISCLAIMER: Stanley Grixti - 9H1LO will hold NO RESPONSIBILITY and offers NO GUARANTEE on the operation of this kit, whether supplied in kit or ready-built form.
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