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HarryA

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HarryA last won the day on November 13 2020

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  1. Bear in mind the headroom for the LM388 is 3 volts. The headroom voltage refers to the actual voltage drop across the regulator that must occur during operation. So that means that the most you can get out of the above circuit is 9 volts. Minus the drop across the 0.3 ohm resistor. You maybe better off using your one transistor circuit if you do not need the power/current for extended periods. If so perhaps there is a spice model for the IRFB4110? You could run it in the LTspice simulator and/or I could run it in the TINA-TI simulator. Also there may be a similar transistor that there is
  2. The max for the LM388 is 12 amperes: Look at the the Buck Converter here; one reviewer is pushing it to 25 amperes with a fan/blower cooling. https://www.amazon.com/Anmbest-Converter-Adjustable-Regulator-Protection/dp/B07R832BRX/ref=sr_1_41?crid=3ETDJKMX4K9ZO&dchild=1&keywords=dc+12v+converter+step+down+module&qid=1610919636&sprefix=dc+12v+step+down+converter+12v%2Caps%2C407&sr=8-41 I should get a kick-back from Amazon.com for all the times I reference them.😉
  3. You do not need the bridge diode nor the 4700 mfd capacitor but keep the 0.1 mfd as it is typically in voltage regulators of that type. You may need heat sinks and heat sink compound; look up "lm388 pdf" files for more information. This illustration is set up for 5 volts:
  4. It may work but as you say it is not very efficient. You can stack voltage regulators to get the current you need if you wish to roll our own. See the 4-20 volt 20 ampere circuit here: https://www.eleccircuit.com/high-power-supply-regulater-0-30v-20a-by-lm338/ Also you can buy a motor controller that may work for you - rated 30 amperes. With luck you may get one that works - read the reviews. https://www.amazon.com/RioRand-7-80V-Motor-Controller-Switch/dp/B071NQ5G71/ref=sr_1_4?dchild=1&keywords=adjustable+voltage+regulator&qid=1610728630&sr=8-4 Now I see " it i
  5. There is a good write-up here that maybe helpfu- using the Knowles Electronics, Inc. EK23029 electret condenser microphone: http://oldbird.org/mike_home.htm Also see: https://en.wikipedia.org/wiki/Microphone#Application-specific_designs and https://www.allaboutbirds.org/news/capturing-natural-sounds/
  6. The best you can do is to start at the output transistors and work your way back through the circuit. It is impossible to diagnose homemade circuits at a distance as there are just to many places to go wrong. For others never build something you can buy cheaper. Get two at 8$ each - one for parts. https://www.ebay.com/itm/Stabilized-Continuous-Adjustable-DC-Regulated-Power-Supply-Kit-0-30V-2mA-3A-L/353345066780?hash=item524501d71c:g:JjsAAOSw~QteWLkt
  7. To Calculate C when Vf, R, t and Vi are known; see https://hoven-in.appspot.com/Home/Blog/rc-discharge-calculator.html For R = 4 (0.004k) ohms, Vstart = 400v, Vend = 300v, and time = 15ms I got C = 13035 μF.
  8. Also consider power oscillators. Like the royer oscillator used in induction furnaces. Your capacitor would be part of the oscillator circuit thus solves the resonance problem. I tried one in LTspice like the one in this link; got oscillations similar to your voltage and current display above. I could not find a Spice model for an avalanche diode so I used a low voltage zener for the BYV26E. Searching on "royer oscillator" brings up lots of hits. https://krishnamurthy1995.wordpress.com/2016/04/20/royer-oscillator-based-induction-heater/
  9. I would think that the transformer would destroy the nature of the resonance circuit. Are you thinking that if you find the resonance frequency of the real circuit then as the water is consumed it would change the resonance frequency by the change in capacity of the cell/capacitor? You may wish to make sure that you are getting the results you expect by driving the circuit with a fixed frequency and seeing if you get any results at all. By the way there is an online signal generator that you can sweep your circuit with to find the resonance frequency and drive the pll for a first te
  10. I believe the only way one may detect resonance is with something that has a memory be it human or microcomputer. One needs to know that it is passing resonance peak and then backup. A microcomputer could store values and keep comparing the values until the current value is less then previous values. There are current detectors that encircle one lead that maybe less intrusive than a direct connection to the capacitor if you can find one that is sensitive enough.
  11. If the spikes are only there while rotating the potentiometer then it is a bad pot. If they are there in cc mode always then you can trace them back through the op amps output to inputs until you narrow down the source.
  12. You need to post the schematic you are working from. Perhaps start a new thread with a similar title? A fresh start is always a good start 🤠
  13. Your cells should charge up to 4v or so; I would think them to be okay. The BMS board is for charging. There are cells with protection built-in but they are expensive. There are simple devices you may add to a cell for such protection: Here is a video on single cell protection: https://www.youtube.com/watch?v=oIE6bWj-lSU
  14. What controller? What/which NTC temperature sensor? Are you asking how to acquire the data from the sensor into the controller?
  15. You could use three 3.7v cells to make up a 11.1/12v battery. For example three 9800 mAh would be; 9.8 Ah * 11.1 or 108.78 Watt hours. The valve only use 4.8 watts and the standby current for the IR unit is only 50 microAmps. For example: https://www.ebay.com/itm/Rechargeable-Batteries-Li-ion-3-7V-Battery-Cell-For-Flashlight-Headlamp/133513298232?epid=27041280478&hash=item1f16034138:g:NGkAAOSwPSNfgRa4 Finding a charger that charges an odd number of cells is a challenge. There are slot chargers that charge cells in parallel that would be helpful if you can find one. The 11.1
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